GPT-5.4 Pro is very good, at the very least comparable with Opus 4.6.
Some people on my team have switched to Codex in the last month citing that it's currently slightly better.
If you have a good workflow with CC I wouldn't switch, but if you're deciding whether to use one or the other, maybe give Codex a shot.
Actually I am currently using claude code mainly for the UI purpose. I consider myself good developer and all the design and architectural decisions are taken by me. I use claude mostly for the code quality it gives. Do you think codex has surpassed claude in terms of UI and code quality ?
I haven't used Codex for UI work, but you might find this helpful: https://developers.openai.com/blog/designing-delightful-fron...