So, not uBlock or whatever as everyone’s aware of that.
Mine (all Firefox):
Video Speed Controller. LOVE this one. A tiny widget appears on any video showing current speed and you hit a key to +10% / -10% (I have mine mapped to [ and ]). You can also hide the little widget (v) if you’re watching a movie etc.
Very handy for sites that don’t support changing video speed or have limited options.
Quick cookie manager - Allows you to delete all cookies on a page that you’ve visited. Very handy when “reject all” leaves you with like 20 cookies anyway.
Netflux - 1080p Netflix on Linux. Can be a little fiddly at times but it does work.


Alas, not that many people know about it. If they were, they would not be using Chrome-based browsers as the new (& neutered) version of uBO for chrome is rather limited.
Beside uBO, I barely use any extension as it can do (well) so many things already beside blocking ads: fingerprinting, removing cookies popup and consent notifications, removing all the shit I don’t want to see from most websites (looking at you, YT Shorts):
Save the Qwant one, they all are in the ‘recommended extensions’ section on the Mozilla website. (edit: I think so, I have not checked)
On the browser I use for more personal/private stuff I don’t have any extension beside uBo… I would not go on the Web, or barely on a few selected websites, without using uBO to be honest: every time I’m faced with a non uBO-protected browser I feel like dying. Too much tur… ads, I mean. It’s just not tolerable.