I went through evaluating a bunch of frameworks. There was Langchain, AG2, Firebase Gen AI / Vertex / whatever Google eventually lands on, Crew AI, Microsoft's stuff etc.
It was so early in the game none of those frame works are ready. What they do under the hood when I looked wasn't a lot. I just wanted some sort of abstraction over the model apis and the ability to use the native api if the abstraction wasn't good enough. I ended up using Spring AI. Its working well for me at the moment. I dipped into the native APIS when I needed a new feature (web search).
Out of all the others Crew AI was my second choice. All of those frameworks seem parasitic. One your on the platform you are locked in. Some were open source but if you wanted to do anything useful you needed an API key and you could see that features were going to be locked behind some sort of payment.
Honestly I think you could get a lot done with one of the CLI's like Claude Code running in a VM.
