Ublock Origin is an obvious one, but I also can’t stand not having Foxy Gestures anymore. It adds customizable mouse gestures, so you can set it up to have easy swipes to go back a page, reload a page, close a tab, etc, and it feels wonderful and smooth to use compared to just using the traditional buttons to do everything. Honestly it’s kinda wild to me that this isn’t more popular now that people are so used to phone gestures. It’s good for the same reasons!
It occasionally renders incorrectly, but yeah, I haven’t been able to find a dark-mode extension better than this!
I just assumed it would be terrible because it’s a hard problem to solve generally, but like 98% of the time I don’t even realize it’s on (and it’s really easy to turn off). It’s seriously incredible.