All of the Claude models are smarter than the GPT models. I had a few threads that I migrated from GPT to Claude and every single one Claude pointed out problems. Two examples:

1. In one, I was putting together a server build. Claude correctly pointed out some incompatibilities in some parts that GPT had recommended.

2. In another chat, I had asked for help interpreting lab results and suggesting supplements. Claude pointed out that GPT was over-interpreting the results and suggesting things that weren't backed up by facts.

I presented Claude's response back to GPT and in both of these specific cases, GPT admitted it was wrong and didn't have any rebuttal. It's hard to say without doing a more scientific experiment whether GPT is indeed worse, but anecdotally I find myself pointing out flaws in Claude's reasoning far less frequently than GPT, especially with Opus.

Another less important distinction: GPT has a very distinct writing style that heavily formats responses and repeats itself a few times. Claude is succinct and mostly writes like a person might. It's easier to talk to and feels less "cringe" and sycophantic.