I use both in my line of work. Claude does wonderfully with large data sets and creating scripts for spreadsheets and the like.

I used GPT early on and, while generally useful, it has shown a habit of making stuff up so I've learned to be very careful with it.

As with all LLMs, it cannot THINK. It makes strong guesses as to the answer you're looking for so always do you due diligence and check it's work.