Personalization is super important (in any software), it's a shame that in general, it's not being the focus of most of them.
I prefer fast stable bugfree chromium
The experience was incredibly sub par on Android. I tried browsing a video heavy subreddit, and FF just hung (well, all videos stopped playing, which is what I was there for).
I want to use it, but if it can't manage my base use case, I can't warrant it.
I will try again one day, I'm sure.
But, from my perspective, just having uBlock Origin installed in the extensions is a huge differentiator, that gives most pages a lot of speedup. Stylus can also be helpful to fix some suboptimal mobile designs.
Then there's absolutely infuriating stuff like the address bar and tabs disappearing when scrolling, which is fine, but it can be really fucking annoying trying to get it to show up again. It doesn't respond properly, sometimes I'll have to scroll back up a whole page before it does anything and all I wanted to do was switch tabs, so I have to scroll back down when I come back. Makes me want to punch an FF developer.
You could always make it not to hide when scrolling. I btw use gestures to switch tabs via an extension, works great.