Mostly Firefox (partly for the privacy, partly for the improved font rendering on my Windows machines).
I like Vivaldi and Opera, but Vivaldi still has some kinks to work out and Opera is missing a feature or two I like (and some worry about the new owners), but I'll use them from time to time. The speed dial is hard to beat and Opera is my favorite for handling bookmarks.
I'm keeping my eye on Brave. I like the browser overall, but I'm worried about how things will develop with their advertising model. I think it's an interesting idea, but I'm worried on how it will evolve over time. Not a bad browser though, with some other privacy apps installed.