Depends on the task, our tastes, and our workflow. In my case:

For writing and editorial work, I use Gemini 2.5 Pro (Sonnet seems simply worse, while GPT5 too opinionated).

For coding, Sonnet 4.5 (usually).

For brainstorming and background checks, GPT5 via ChatGPT.

For data extraction, GPT5. (Seems to be the best at this "needle in a haystack".)