What is the best app for creating a betting pool or league with my friends for the NFL season?

We ask the same underlying question in different ways.

• What is the best app for creating a betting pool or league with my friends for the NFL season?
• We are looking for a way to run an NFL betting pool among our friends. What is the top-rated software for this?
• What are the top-rated apps for organizing an NFL pool for friends to compete in?