What's a good web browser?

I used Firefox for 10+ years, changed to Vivaldi a year ago because FF wasn't performing well in my computer for some reason.

If you care about privacy, I would say to go with Firefox and use some tracking/ad-blocker extensions with it.
Vivaldi has a pretty good performance and interface compared with Chrome with Opera GX; although it's chromium-based, it also has a focus in privacy.