Consider Fennec instead of Firefox -- I just switched yesterday, and I think the only difference is that Fennec is usually a couple of versions behind because it removes some Mozilla crapware.
Fennec also lets you install any add-on from addons.mozilla.org through a tedious process,* which is still an improvement over Firefox release/beta on Android. The only channel of Firefox that supports this process on Android is the nightly channel.
What about Firefox Focus? It's private by default and VERY unbloated. The ephemeral nature of sessions also forces me to not leave a hundred tabs open.
There's a workaround to support pretty much any FF extension at this point -- but you have to create a "collection" with your firefox account and then point your Android FF install at that collection. Not too hard, but a little bit of a PITA. If you're like me and maintain the same couple dozen extensions on every FF install, though, it actually works pretty well.
