I started browser life (well, almost) with Firefox, later switched to Pale Moon (still my std browser) and use(d) Vivaldi for stuff that doesn't work under PM. I also had Vivaldi as default under Android.
However, the other day, after yet another bloated Vivaldi for Android update I decided to try Firefox for Android (f-droid version), as Vivaldi is not only bloated but is getting slower with every release. MUCH better. It's faster, both for startup and in use and it supports Firefox extensions. The latter is a killer feature as I now can control cookies under Android as I can under Linux (Cookie AutoDelete extension). Hooray!
Not stopping there, I also installed LibreWolf (a Firefox descendant) on my Linux desktop. And I have to say, it's again much better than I expected though I am not sure it'll fully replace Vivladi any time soon.
I for one am new officially a Firefox fanboi :-)