I’ve gone between a few but on desktop it’s Librewolf. Just like Firefox but more privacy by default. On Android I’ve tried Fennec, Brave, Iceraven, and Mull. Out of all of them Iceraven has been my favorite simply because of its support for desktop extensions.
I like LibreWolf, but I also use Falkon on systems that can’t handle that. Falkon has barely any extensions, and none of them are anything big (there’s no uBlock Origin or Privacy Badger or anything); but it does support Greasemonkey scripts.
In text mode, I like w3m because it can display images. In all other respects, text browsers are pretty much identical to me.
On Android, I found that I like Mull more than anything else; but Bromite is good. FOSS Browser is also pretty great.
However, I begrudgingly use iOS, rather than Android, and my pick for the rotten Apple has got to be SnowHaze. This browser is FOSS and privacy-focused, with fine-tunable privacy and security settings that can even be set differently for individual tabs. Much better than anything I could make with Safari extensions.