I also prefer Claude after trying the same options as you.

That said I can't yet confidently speak to exactly why I prefer Claude. Sometimes I do think the responses are better than any model on ChatGPT. Other times I am very impressed with chatGPT's responses. I haven't done a lot of testing on each with identical prompt sequences.

One thing I can say for certainty is that Claude's UI blows chatGPT's out of the water. Much more pleasant to use and I really like Projects and Artifacts. It might be this alone that has me biased towards Claude. It makes me think that UI and additional functionality is going to play a much larger role in determining the ultimate winner of the LLM wars than current discussions give it credit for.