Most comparisons rank CrewAI as the more production-ready of the two. On the one question that decides whether you need a third subscription just to see what your agent did, AutoGen actually comes out ahead.
CrewAI and LangChain both get a demo working in an afternoon. The real difference shows up once you need to trace a wrong answer, test the agent, and keep one customer's data out of another's.
Semantic Kernel and LangChain look close to interchangeable on a feature table. The gap that actually costs you time shows up later, in tracing, testing, and running one agent for more than one paying customer.
LangChain and LlamaIndex split on orchestration versus retrieval, but the choice that actually costs you later is which one is easier to trace, test, and isolate per tenant. Here's the real comparison, plus where CrewAI fits.