I'm geniunely asking, what are the alternatives that are fast, have builtin sync, and can block ads on android? I've tried firefox, and while it's gotten better on desktop, in my experience it struggles to play youtube videos on mobile, and the ui is basically unusable on a tablet/foldable.
Since the transition to GeckoView the tablet ui is just scaled up mobile ui, with no tab-bar and no desktop sites by default. For some reason mozilla has marked it as a feature request instead of a bug (which I argue it is, as it used to have those features, as do all of the competing browsers), and successfully have been ignoring for 3 years (here's the discussion on mozilla connect, but there used to be a github issue before that).
As for youtube, I need a browser to use https://chatreplay.stream/ . For everything else of course there are NewPipe, ReVanced, and LibreTube
Enthusiasts don't like to hear it, but Edge, which is Chromium, has a built in adblocker which can be adjusted to also block safe ads.
It has a genuinely good sync with an account that nearly everyone has. The only reason to dislike Edge post-Chromium is the company Microsoft, but it's IMO the best Chromium browser, for both Windows/Android.