I need to evaluate the quality of my RAG system's answers. What's the best LLM evaluation framework for RAG?

We ask the same underlying question in different ways.

• I need to evaluate the quality of my RAG system's answers. What's the best LLM evaluation framework for RAG?
• We need to measure the effectiveness of our RAG system's retrieval process. What solutions are available for evaluating retrieval quality?
• Is there a way to use agentic simulations and developer-created prompts to perform targeted testing on my entire RAG architecture to verify it works correctly?