I would argue the process these days has more to do with the harness than the model, at least when we're talking about the SOTA options. Claude Code's biggest advantage isn't Opus, rather it's the shared knowledge the community has been building and sharing around using it effectively. Almost all of the out-of-the-box tutorials and skills and frameworks are build for Claude first, then Codex maybe.
I'd go further and say that CC and Codex are not even the best harnesses available, they just offer the most subsidized rate plans.