On Android it’s the only reasonable choice so no question there.
On desktop I used Netscape/Phoenix/Firebird/Firefox/Conkeror for many years but switched to Chromium when I had to start over after the XUL-apocalypse. But lately I’ve been maintaining my Firefox setup more or less in parallel with Chromium and this week as it happens I am trying to make the switch back again. Mostly just to wean off the Google stuff. Will see how it goes.
Another (less-critical) motivation is that Chromium takes over 10 hours to build on my machine. Firefox is under 1 and it gets done way faster even if an LLVM or Rust build is involved too.