I think it depends on the domain. For example, GPT-5 is better for frontend, React code, but struggles with niche things like Nix. Claude's UI designs are not as pretty as GPT-5's.
I often would use Claude to do a “make it pretty” pass after implementation with GPT-5. I find Claude’s spatial and visual understanding when dealing with frontend to be better.
I am sure others will have the exact opposite experience.
But after openai started gatekeeping all their new decent models in the api, i will happily refuse to buy more credits, and rather use foss models from other providers (I wish claude had proper no log policies).