CodeRabbit in particular is gold here. I don't know what they do but it is far better at reviewing than any AI model I've seen. From the deep kinds of things it finds, I highly suspect they have a lot of agents routing code to extremely specialized subagents that can find subtle concurrency bugs, misuse of some deep APIs etc. I often have to do the architecture l/bug picture/how this fits into project vision review myself, but for finding actual bugs in code, or things that would be self evident from reading one file, it is extremely good.