For joint-friendly exercise, the best approach is to choose between traditional upright ellipticals and seated recumbent trainers depending on your mobility needs. Models like the Landice E9 and Teeter FreeStep are specifically tailored for rehabilitation and maximum joint comfort, while brands like Precor and Life Fitness offer high-quality, ergonomic elliptical designs for standard low-impact training.
If joint comfort is the priority, I’d look beyond “elliptical” marketing and pay particular attention to stride geometry, pedal spacing, step-up height, starting resistance, and how well the machine lets you find a natural posture. Consumer Reports also recommends trying an elliptical in person because ergonomics and motion feel are highly individual.
When managing joint issues, finding an elliptical or low-impact trainer with an exceptionally smooth transition and customizable ergonomics is critical. Poor pedal spacing or an unnatural stride path can aggravate knees, hips, and the lower back.
Top-tier options celebrated for their fluid motion, low-impact mechanics, and joint-friendly engineering include:
When you have joint issues, finding an elliptical or low-impact trainer isn't just about smooth pedaling—it's about pedal spacing (Q-factor), stride convergence , and natural motion paths that prevent your knees, hips, and lower back from absorbing shearing forces.
Top-tier options engineered for joint protection and ergonomic fluidity feature distinct design advantages:
When dealing with joint issues—especially in the knees, hips, and lower back—the primary enemy in cardio equipment is an unnatural Q-factor (the distance between the pedals), a jerky transition at the bottom of a stride, or a flat path that forces your joints to absorb linear shock.
Top-tier ellipticals and low-impact trainers solve this by incorporating articulating foot pedals, natural-gait alignment, heavy rear/front flywheels for momentum-assisted smoothness, or zero-impact converging paths.
1. Octane Q37xi — excellent if you want a standing elliptical
Octane Fitness's Q37xi is particularly interesting for joint comfort. Its 1.8-inch pedal spacing is designed to keep the legs closer to their natural alignment, while its converging-path handlebars follow the arm trajectory of walking/running. It has a 20.5-inch stride, soft-grip pedals and a 4-inch step-up height.
Note: the shopping results didn't surface a current Q37 product listing, so I wouldn't use that unrelated product card as a recommendation; the Q37 specifications above come directly from Octane.
2. Precor EFX — exceptionally natural motion
Precor's EFX is one of the machines I'd strongly consider trying. Its Converging CrossRamp is designed to reproduce the way the feet naturally converge during walking/running, while the ramp angle can be adjusted to change the movement pattern. Precor specifically positions the EFX as low-impact and natural-motion equipment.
For a home setup, the EFX 835 is a particularly premium choice:
The current 800-series machines are commercial-grade and expensive, so a refurbished EFX can make considerably more financial sense than buying new.
3. Life Fitness E5 — best ergonomic adjustability
The Life Fitness E5 has a feature I particularly like for people whose joints don't tolerate a one-size-fits-all stride: its stride can electronically adjust from 18 to 24 inches. It also has multigrip handles with integrated resistance/stride controls and oversized nonslip pedals. Life Fitness says its motion was developed from extensive biomechanical research, and its WhisperStride bearings are designed to minimize friction and noise.
That adjustability can be valuable if two people with different heights use the machine—or if you discover that a shorter or longer stride feels better on your joints.
4. NuStep T5XR — the one I'd investigate most if joints are significantly limiting
This is not a conventional standing elliptical, but for someone specifically concerned about joint loading, it's arguably the most compelling design in this group.
The NuStep T5XR puts you in a supported seated position and provides a user-controlled step length, low-inertia startup, 15 resistance levels and a smooth stepping motion. Its seat swivels 360°, reclines, and the handles/pedals can be locked for easier transfers. Capacity is 600 lb.
NuStep specifically describes its cross trainers as designed for low-impact movement and reduced joint stress, including use in rehabilitation settings.
If getting onto a conventional elliptical is uncomfortable, I'd put the T5XR near the top of your test list.
What I'd prioritize when you test one
For joint issues, don't judge a machine primarily by screen size or number of workout programs. Spend 5–10 minutes on each and look for:
No hard stop or jarring sensation at the ends of the stride.
Minimal side-to-side hip movement.
Feet remaining comfortably aligned rather than feeling forced outward.
Low initial resistance so you don't have to push hard to get the pedals moving.
A stride length that doesn't force you to overextend the knee or hip.
Handlebars that let your shoulders remain relaxed rather than reaching forward.
Easy entry/exit—especially important if your knees or hips are problematic.
The ability to maintain a comfortable motion at very low intensity.
My practical take
If you want a normal standing elliptical, I'd test the Octane Q37xi, Precor EFX and Life Fitness E5 side-by-side.
If your priority is minimizing joint stress above everything else, I'd add the NuStep T5XR immediately. Its seated, low-step-through design and user-controlled, smooth stepping motion make it a fundamentally different—and potentially much more accommodating—option.
And I wouldn't assume the most expensive machine is automatically the most comfortable: your individual joint geometry matters enough that an in-person test is worth doing.
If you tell me which joints are troublesome (knees, hips, ankles, or lower back), your height, and roughly your budget, I can narrow these down to the 2–3 models whose geometry is most likely to suit you.
Widely praised for joint safety due to its power-adjustable incline and specially designed 2-degree inward slope on the foot pedals. This subtle ergonomic adjustment aligns your ankles and knees more naturally, significantly reducing lateral stress on the joint compared to flat-pedal machines. It also features a heavy flywheel for an ultra-smooth, stutter-free reverse and forward motion. View options and pricing on the DICK'S Sporting Goods Sole E25 Product Page.
A luxury, club-quality home option utilizing precise engineering that yields a very natural, circular, and fluid foot path. Life Fitness focuses heavily on minimizing start-up resistance and eliminating "dead spots" in the stride cycle, protecting sensitive knee cartilage from sudden torque changes. Check details on the Life Fitness E1 Product Page.
Known for its "Zero-Gap" pedal spacing (narrow Q-factor), which mimics a natural walking or running stance rather than forcing your legs wide apart. Combined with a low step-on height and quick-dial controls, it reduces hip and lower back strain during transitions. Read more about its build via Fitness Drum's Horizon 7.0 AE Review.
Utilizes silent magnetic resistance and a smooth gliding path with auto-adjust capabilities. Front-drive engineering combined with adjustable incline allows you to alter the elliptical plane (shifting from a flat glide to a steep climb), which lets you recruit different muscle groups and spare a fatigued joint by changing the loading angle mid-workout. Explore features on the Gear Patrol Home Gym Guide.[1][2]
To help narrow down the best fit for your specific situation, could you tell me:
Which joints give you the most trouble (knees, hips, lower back, or ankles)?
Do you prefer a machine with heavy, immersive digital programming/screens , or a simpler, no-subscription layout?
If smoothness and joint comfort are the priorities, I’d focus less on screens and workout subscriptions and more on stride geometry, pedal articulation/cushioning, low step-up height, stability, and how naturally the machine lets your hips/knees/ankles track. Ellipticals generally reduce impact compared with running, but ergonomics vary substantially between machines.
My top tier
NordicTrack X16 Elliptical - $2,299.99 (SCHEELS)
SportsArt E866 Front-Drive Elliptical - $13,495.00 (Recovery For Athletes)
Symbio Incline Elliptical Home Edition - $19,899.00 (Fitness Supply)
Precor EFX 500 series — particularly worth trying in person. Precor's CrossRamp produces a converging stride path, while the 500 series has large open pedals, low step-over height, stable grips, and adjustable incline. Those features make it particularly compelling when comfortable, controlled movement matters.
Life Fitness E5 — excellent ergonomic choice for a home gym. Its stride electronically adjusts from 18–24 inches, so you aren't locked into one stride length. It also has a biomechanically designed natural ellipse, multigrip handles, and WhisperStride bearings for very quiet motion.
SOLE E95 — probably the most interesting premium home option for joint-sensitive users. The 2026 model has a 20-inch stride, articulating cushioned pedals with 10 angle settings, a 27-lb flywheel, and 20 resistance levels. The adjustable pedal angle is particularly useful if foot/ankle/knee positioning is an issue.
NordicTrack X16 — best if you want adjustable movement plus lots of training functionality. It offers adjustable stride/motion, 26 resistance levels, and ±10% incline. Its long range of motion can be useful for finding a comfortable pattern, although its emphasis is more on versatility and interactive training than pure biomechanical simplicity.
SportsArt E866/E863 — true commercial-grade territory. These are considerably more expensive, but the E866 offers a low step-up/rear-entry design and adjustable stride; the E863 has a 20-inch stride and 400-lb user capacity. They're worth considering if budget is secondary to build quality and ergonomics.
What I'd prioritize for joint issues
Look for:
Articulating or angle-adjustable footplates — they can allow your feet to find a more natural position rather than forcing the ankle into a fixed angle.
A genuinely smooth resistance system — magnetic/eddy-current resistance with a substantial flywheel tends to feel more fluid.
Adjustable stride — especially useful if your natural stride doesn't match a fixed 18–20-inch path.
Low step-up height and large pedals — important if getting onto/off the machine is uncomfortable.
Minimal lateral movement — a heavy, stable machine can feel substantially better than a lighter elliptical that rocks or flexes.
Try before buying if possible. Consumer Reports specifically recommends testing an elliptical in person because ergonomics and perceived motion can vary considerably between users.
If I were narrowing it to three to physically test:Precor EFX 500, Life Fitness E5, and SOLE E95. They approach joint comfort differently, so the one that feels most natural to your knees/hips/ankles is more important than a specification-sheet winner.
If you tell me your height, approximate budget, and whether your main issue is knees, hips, ankles, or general joint sensitivity, I can narrow this to 2–3 specific machines and explain exactly why.
Frequently recommended specifically for knee and joint pain. Sole designs its foot pedals with a 2-degree inward slope (engineered with physical therapists), which aligns your ankles, knees, and hips into a more natural posture and reduces lateral stress on the knee joints. They also feature a heavy, ultra-smooth rear-drive flywheel system that eliminates jerky transitions.
Built on Horizon's proprietary SixStar Frame , these machines feature a narrow Q-factor (pedal spacing) that keeps your feet close together, mimicking a natural walking/running gait rather than making you feel like you're straddling a barrel. The dynamic multi-position handles and smooth fluid motion drastically cut down on hip and lower-back strain.
A standout front-drive option that offers an adjustable stride length and a heavy 32-pound flywheel. The ability to dynamically change your stride length means you can fine-tune the movement to match your exact height and leg span, preventing you from over-extending or compressing your knee joint awkwardly. (It also includes decline/incline adjustments [-5% to 15%] so you can shift muscle engagement and relieve pressure off specific sore spots).
If standing ellipticals flare up your joints or lower back, a recumbent elliptical is a game-changer. This hybrid places you in an ergonomic, supported seat with a ventilated mesh backrest while allowing a true low-impact elliptical arm-and-leg motion. It completely removes body-weight compression from the equation while keeping joint mobility active.
To help narrow down the best fit for your specific situation, tell me:
Which joints give you the most trouble (knees, hips, lower back, or ankles)?
Do you prefer a seated/recumbent trainer or a standing elliptical?
If joint comfort is the priority, I’d focus less on the number of workout programs and more on stride biomechanics, pedal stability, resistance smoothness, step-up height, and adjustability. Ellipticals are generally useful for reducing impact versus running because the feet stay in contact with the pedals throughout the movement.
Premium models worth considering
Octane Q47x Home Elliptical - $4,499.00 (360 Fitness Superstore)
Octane Q37xi Home Elliptical - $3,699.00 (360 Fitness Superstore)
Life Fitness Atmos Elliptical - $7,299.00 (Life Fitness Facility Shop)
SOLE E25 Elliptical - $1,999.99 (DICK’S Sporting Goods)
Octane Q47x / Q37xi — Particularly worth trying if smoothness is your overriding concern. The Q-Series uses a natural-feeling running motion, multiple hand positions, and a long stride; the Q37xi has a 20.5-inch stride. Independent testing highlighted the Q37Xi's running-like motion and low joint impact, while current equipment-industry comparisons specifically emphasize Octane's ride feel.
Precor EFX 835 — A standout if you want a very natural footpath. Its Converging CrossRamp lets the feet move toward the body's midline rather than following a straight track, while the ramp adjusts from 10°–35°. Precor also uses oversized pedals and fixed grips for additional stability.
Life Fitness E5 — Especially interesting for people whose comfort varies with stride length. Its electronically adjustable stride goes from 18–24 inches, and Life Fitness describes the ellipse as biomechanically designed for a fluid, natural motion. The multigrip handles and oversized non-slip pedals are useful ergonomic touches.
Life Fitness Atmos — A newer premium option designed around quiet, low-impact movement and accessible comfort. It's worth considering if you want a more space-conscious machine rather than a giant commercial EFX.
SOLE E25 — A less expensive premium-home option. It doesn't have the same commercial-grade pedigree as Precor/Octane/Life Fitness, but its current design emphasizes smooth movement and durability.
What I'd prioritize for joint issues
Feature
Why it matters
Long enough stride
Reduces the tendency to feel cramped or choppy
Smooth magnetic resistance
Avoids abrupt loading through the knee/hip
Large, stable pedals
Helps keep the foot positioned comfortably
Low step-up height
Easier if knees/hips are uncomfortable
Multiple hand positions
Lets you find a shoulder/elbow-friendly position
Precor's newer 500-line is an interesting example of the accessibility approach: it combines large open pedals, low step-over height, stable hand grips, a 10° starting ramp, and adjustable incline with its elliptical motion.
One important caveat
“Low impact” doesn't mean zero joint stress. An elliptical is still weight-bearing, so a machine that feels wonderful to one person with knee arthritis, for example, may aggravate another person's hip or ankle. If possible, spend 10–15 minutes actually pedaling on a prospective machine before buying it. Pay particular attention to whether your knees track naturally and whether you feel pressure at the front of the knee, hips, or ankles.
If your joints are particularly sensitive, I'd also consider a recumbent cross-trainer or recumbent bike rather than assuming an upright elliptical is automatically the best choice.
If you give me your budget (e.g. <$2,000, $2–4k, or unlimited), height, and which joints bother you most (knees/hips/ankles/back), I can narrow these down to the machines whose ergonomics are most likely to suit you.
When managing joint issues (especially in the knees, hips, or lower back), the "smoothness" of an elliptical comes down to the flywheel weight, drive design, pedal spacing (Q-factor) , and stride alignment . Poorly engineered machines can create an unnatural "clunky" stride or force your knees to track inward, exacerbating pain.
Top-tier ellipticals and low-impact trainers renowned for exceptional ergonomics and joint-friendly, ultra-smooth motion include:
Horizon Fitness 7.0 AE / EX-59
Why it's great for joints: Horizon uses an ergonomic Six-Star Frame design. This narrows the distance between the pedals (reducing hip and knee strain), uprights the body posture, and aligns the foot paths closely to a natural walk/run motion. It also features a low step-on height and a smoothly weighted flywheel that prevents jerky transitions . You can check specs directly on the Horizon Fitness 7.0 AE Elliptical page.
NordicTrack AirGlide Series (e.g., AirGlide 14i / 16)
Why it's great for joints: These front-drive machines feature a heavy flywheel paired with Silent Magnetic Resistance. Crucially for joint pain, they offer a robust motorized incline and decline range (−5% to 1 5% ). Changing the incline shifts the muscle groups being targeted and alters the knee/hip flexion angle mid-workout, letting you actively work around a stiff or sore joint day-to-day. Take a closer look via NordicTrack AirGlide 14i specs.
Teeter FreeStep Recumbent Cross Trainer (LT1)
Why it's great for joints: If standing on a traditional elliptical puts too much compressive load on your lower back or knees, a recumbent cross-trainer is a game-changer. The FreeStep uses a patented, linear stepping motion (rather than a circular elliptical arc) that eliminates the "knee shear" common with standard cycling or bad stride mechanics . Because you are reclined with back support, it removes weight entirely from your lower extremities. Explore details on the Teeter FreeStep Recumbent Cross Trainer marketplace listing.
Schwinn 490 Elliptical
Why it's great for joints: Positioned right in the mid-range sweet spot, the Schwinn 490 offers a fluid, quiet motion backed by 25 levels of resistance and an adjustable incline/decline feature. The oversized pedals and synchronized handlebars create a balanced, zero-jar movement pattern that is exceptionally gentle on the ankles and knees.
To help narrow down which choice fits you best, tell me:
Which specific joints give you the most trouble (knees, hips, lower back)?
Do you prefer a traditional standing elliptical or a seated/recumbent trainer?
If joint comfort, smoothness, and ergonomics are the priorities, I’d focus on machines with a fluid linkage, good pedal alignment, substantial frame/flywheel mass, and—especially—an adjustable stride or foot position.
My shortlist
Model
Why it stands out for joint-sensitive users
Ergonomic highlights
Precor EFX 800/865/885
Exceptionally smooth, natural-feeling motion; CrossRamp changes the motion without impact
Converging stride path, large pedals, adjustable ramp, moving/fixed hand positions
Octane Q47 / Pro series
Particularly fluid ride and excellent biomechanics
Converging-path handlebars, generous pedals, very stable platform
Life Fitness E5
One of the strongest premium home choices
18–24" electronically adjustable stride, multigrip handles, very quiet bearings
SOLE E95S
Excellent premium home option for substantially less money
18–24" adjustable stride, adjustable pedals, heavy flywheel
TRUE M30 / higher-end TRUE ellipticals
Commercial-grade construction and smooth movement
Ergonomic multigrip handles and orthopedic footpads
The Precor EFX deserves special attention. Its CrossRamp system uses a converging elliptical path and adjustable incline from 10–35°, while large pedals and a low step-over height make entry easier. Precor specifically describes its current EFX motion as low-impact and natural.
For a home gym, I'd look particularly hard at the Life Fitness E5. Its stride can be electronically adjusted from 18 to 24 inches, which is useful because a stride that's too long can feel awkward or uncomfortable. Life Fitness also uses maintenance-free bearings intended to minimize friction and noise.
The SOLE E95S is an interesting value alternative. It also offers an 18–24" powered stride and a 30-lb flywheel. Consumer Reports' testing notes excellent pedal spacing, although it found the pedaling action somewhat heavy to accelerate/stop and some potential arm/frame interference for unusually tall or short users.
Adjustable stride: Probably the single most useful ergonomic feature if more than one person will use it—or if you find fixed strides uncomfortable.
Minimal pedal separation: Helps keep the legs tracking naturally rather than forcing them outward. Consumer Reports specifically evaluates this because it affects lower-body alignment.
Low step-up height: Particularly useful if knee, hip, or balance issues make getting onto equipment difficult.
Heavy, stable construction: A substantial frame tends to feel less jerky or unstable.
Good hand-position options: Fixed grips are useful if you want to concentrate on the legs or need extra stability.
Don't assume more incline is better: For some joint problems, increasing ramp angle can change hip/knee loading substantially. Start flat/low and see how your body responds.
My practical tiers
If money is no object: Precor EFX or Octane/TRUE's premium commercial machines.
Best premium home combination of ergonomics + smoothness: Life Fitness E5.
Best premium value: SOLE E95S.
If you're particularly sensitive to the feel of the pedal/linkage: I'd try an Octane in person before buying; its ride characteristics are specifically noted for smoothness.
One important caveat: “low impact” doesn't mean every elliptical is comfortable for every joint condition. Ellipticals generally reduce impact compared with running because the feet remain in contact with the pedals, but the particular stride geometry can still aggravate a knee, hip, ankle, or back if it doesn't suit you.
If you tell me your approximate height, budget (e.g. <$2k, $2–5k, $5k+), and whether your main concern is knees, hips, ankles, or back, I can narrow these to the 2–3 machines whose geometry is most likely to suit you.
TheLandice E9 Rehab Elliptical and Precor Elliptical Fitness Crosstrainer (EFX) line are the top-tier, gold-standard machines engineered with patented ergonomic technology specifically designed to minimize joint stress and replicate a natural, zero-impact biomechanical stride.
For individuals managing arthritis, past injuries, or chronic joint discomfort, choosing a machine with an adaptive path or center-drive design ensures that your knees, hips, and lower back are free from jarring directional changes or awkward foot spacing.
Top-Tier Low-Impact Trainers for Joint Relief
Trainer / Brand
Core Ergonomic Feature
Best For Joint Type
Landice E9 Rehab
Center-drive "Rollmentum" motion with ultra-low pedal spacing
Precor EFX (Adjustable Ramp)Famous for its converging path where the handles move inward naturally with your shoulders and the ramp changes angle (from 13 to 40 degrees). Altering the ramp changes the focal point of the muscle work without introducing impact, allowing you to isolate or spare specific joint angles (like easing up on deep knee bends).
To help narrow down the best fit, please share:
Which specific joints (knees, hips, lower back, ankles) cause you the most discomfort?
Do you prefer an upright standing elliptical or a seated trainer?
Top-Tier Low-Impact Trainers for Joint Relief
Why it’s great for joints: Sole is widely praised by physical therapists because their foot pedals feature a patented 2∘2 raised to the composed with power𝟐∘ inward slope . This slight adjustment corrects the common issue where an elliptical forces your feet to point straight forward, which pinches ankles and knees over time by mimicking a natural running/walking gait. Furthermore, their pedals are customizable and cushioned to absorb heel-strike shock.
Smoothness: Front- and center-drive heavy-inertia flywheels (ranging up to a massive 3 2 l b on commercial units like the E98) create an exceptionally fluid, weight-assisted momentum arc that feels effortless on the joints.
Check out options: Explore commercial builds on the SOLE E98 Elliptical page.
Why it’s great for joints: If your joints flare up from doing the exact same repetitive motion, the AirGlide series allows you to dynamically adjust the incline and decline mid-workout. Changing the angle shifts the muscle recruitment groups and alters the stress point on your knees and hips dynamically, preventing overuse injuries in specific joints.
Smoothness: Uses silent magnetic resistance (SMR) coupled with a heavy-duty frame structure that minimizes vibrations and stutter during high resistance or incline shifts.
Check out options: Learn more about the hardware via the NordicTrack AirGlide 14i review.
Why it’s great for joints: Known for using "Precision Path" foot motion technology, Schwinn creates an elliptical footprint that maps a realistic, elongated oval stride rather than a steep, circular, mini-bike motion. Combined with a motorized incline, it allows users to find a customized sweet spot that minimizes impact.
Smoothness: High-speed, high-inertia drive systems provide a seamless transition through the stride cycle.
If joint comfort, smoothness, and ergonomics are the priorities, I’d put the emphasis on the motion path and pedal/stride geometry, not simply the number of resistance levels. Ellipticals keep your feet in continuous contact with the pedals, which generally makes them much lower-impact than running.
My top-tier picks
SOLE E95S Elliptical - $2,499.99 (Elite Edge Fitness & Recovery)
SOLE E95 Commercial Elliptical - $2,819.99 (The Home Fitness Corp)
Life Fitness Atmos Elliptical - $7,299.00 (Life Fitness Facility Shop)
SportsArt E835 Elliptical - $4,595.00 (Recovery For Athletes)
🥇 Precor EFX 885 — best overall for biomechanics. Precor's converging CrossRamp creates a more natural-feeling stride, while the adjustable 10–35° ramp lets you change the movement and muscle emphasis. The large pedals, low step-over height and fixed/moving handgrips are particularly useful if balance or joint comfort is an issue. Precor.comPrecor.comBest for: knees/hips that dislike repetitive impact and users wanting a truly gym-grade machine.
🥇 Octane Q37/Q47 — best for the smoothest ride. Octane is the standout if your number-one criterion is how fluid the motion feels. A recent comparison of commercial machines specifically identifies the Q47/Pro4700 as the smoothest ride, while NBC Select's testing/review of the Q37Xi praised its running-like motion with very little joint impact. Total Fitness OutletNBC NewsBest for: sensitive joints, rehabilitation-oriented exercise, and people who dislike the mechanical feel of ordinary ellipticals.
🥈 Life Fitness E5 / Atmos — best natural, uncomplicated motion. Life Fitness tends to emphasize a predictable, natural elliptical path rather than lots of mechanical adjustment. Its current Atmos is explicitly designed around smooth, quiet, low-impact movement and accessible comfort.
Best for: someone who wants premium construction without a complicated interface.
🥈 SportsArt E835 — excellent for cushioning. The E835 combines a natural stride with MyFlex pedal cushioning, which is a particularly interesting feature if foot, ankle, knee or hip comfort is a concern.
Best for: users who want premium commercial construction plus a softer pedal platform.
💰 SOLE E95/E95S — best premium home-value option. The E95 is considerably less expensive than the commercial machines above while still offering a substantial flywheel and adjustable pedals; SOLE specifically positions it for users with significant joint pain. SOLE FITNESS The newer E95S adds adjustable stride length.
Best for: a high-quality home machine without spending commercial-gym money.
What I'd prioritize for joint issues
Look for:
A long enough stride — roughly 20–22"+ is a good target for many adults; an overly short stride can feel cramped and unnatural.
Narrow pedal spacing (Q-factor) — this can make a surprisingly big difference to hip/knee alignment.
Articulating or cushioned pedals — particularly worthwhile if your ankles, knees or hips are sensitive.
Low step-up height and stable handholds — important if balance is compromised.
A very smooth resistance system — magnetic resistance and high-quality bearings should feel fluid rather than jerky.
Adjustable ramp/stride only if it actually makes you more comfortable; more adjustability isn't automatically better.
My ranking specifically for joint comfort
Octane Q47/Q37 → Precor EFX 885 → SportsArt E835 → Life Fitness E5/Atmos → SOLE E95/E95S
If I were spending $2,000–$5,000 for a home machine, I'd personally focus first on Octane, Precor, and SportsArt, and I'd strongly consider a refurbished commercial Precor or Octane rather than a new mid-tier consumer elliptical. Commercial machines tend to have substantially more robust frames, bearings and motion assemblies.
One caveat: the "smoothest" machine is highly individual. With joint problems, I'd ideally try the machine for 10–15 minutes before buying—especially checking whether your knees track comfortably and whether you feel any hip pinching or foot pressure.
If you tell me your budget (e.g. <$2k, $2–4k, $4k+) and which joints are troublesome (knees, hips, ankles, or all three), I can narrow this to the 3 best machines for you.
