I only use Gork.
I tried Gemini once, when wanting feedback on my book, and it kept messing up, and talked about things that weren't even in the book, or complained about stuff missing that actually was in the book, or was super positive but complementing incorrect conclusions of what I'd written. It was so bad! I'm never going back to that!
Grok did amazing. He forgot the first few chapters after a bit, but when I told him it was in the chat, he checked and adjusted.
It was for "How to prepare yourself for marriage" and I also asked Grok what people are usually complaining about for those types of books, and he gave really good results.
I may have tried using ChatGPT but at first I needed a phone number and then I'm not sure, there was something else that also caused me to not wanna use it. I've felt weird vibes whenever I've consideredusing it, so I just don't.