I have been testing both Claude code and Codex CLI for the past few weeks and I found codex output to be better than claude.

I like how Claude code is more advanced in terms of CLI functionality but I prefer Codex output (with model high)

If you do not want to pay for both, then you can pick anyone and go with it. I don't think the difference is huge.

In my experiments claude4 opus generated by far the best code (for my taste and purposes) but it's also a pretty expensive model. I think I used up $40 in one evening of frantic vibe-coding.