I currently use both. I see them as two different tools with two different strenths. Kinda like two different helpful colleagues with two different sweet spots.
Copilot = Code completion on steroids. Mind you, it's supposed to be good for starting new ideas but I haven't found the prompts that truly unlock that capability. It try to seed it with a comment but that doesn't often translate into what I want. Could be me? It tends to be more literal.
I realize different markets have different values for $10. But Copilot is an investment not an expense. If you're using it every day it pays for itself and then some.
ChatGPT = a rubber duck. It's great when you have an idea and like to see how that might look freshed out as lines of code.
I also find it useful for my blindspots. For example, I had to do some jQuery yesterday. It had been a couple of years since I last touched jQ. ChatGPT was better than searching for answers.
That said, ChatGPT tends to be more creative. Where I'm able to have a faux discussion on something. Copilot doesn't chat.
I use the free ChatGPT version. I'm considering the paid version. Maybe soon.