In my personal experience, Claude is better at greenfield, Codex is better at fitting in. Claude is the perfect tool for a "vibe coder", Codex is for the serious engineer who wants to get great and real work done.

Codex will regularly give me 1000+ line diffs where all my comments (I review every single line of what agents write) are basically nitpicks. "Make this shallow w/ early return, use | None instead of Optional", that sort of thing.

I do prompt it in detail though. It feels like I'm the person coming in with the architecture most of the time, AI "draws the rest of the owl."