Well, chat.openai.com is down today. I've been using it quite a bit recently, mainly to ask questions about physics and history but also for some low level work help - it's great for fire-once functions I can easily describe.
I don't really want to use microsoft's - the privacy policy and forced "free" feature make it seem dubious. I'd rather pay and have limited control over the data.
Poe.com if you can stand the excessive censoring.
It once refused to review a short story without the author's consent. I had to reassure it that I was indeed the author.