I started using SAM because I didn't need to worry about other cloud solutions besides AWS. I didn't want to add extra complexity that I would not use.

But every time I needed something more complex, I struggled looking at SAM documentation while I could easily find a serverless framework solution.

So I moved to serverless and never looked back.

It has always felt that serverless frameworks was written by developers who actually use the technology while SAM felt like an afterthought from AWS.