I haven't used Firefox since October 2024. Not because of any terms of use or anything, just because my default profile kept resetting all of my settings and sync wasn't working. To be fair, I was using the developer edition, not basic Firefox, but it was enough to make me look for something new.
I have been really happy using Zen. It has had some bugs, especially early on, but over time it has become really solid. I'm also willing to try some of the others, but I typically don't change things often, so I've probably been using Zen long enough that I'll just going to continue using it :)