Not OP, (and Firefox is still my main), but I keep Chromium-based browsers around for Ichigo, an addon which automatically translates raw manga - which is a godsend for avid manga readers like myself who frequently run out of existing translated manga to read. There's also Scan Translator which works in a similar way, but sadly Firefox has nothing like them.

I just spent awhile trying to switch from Vivaldi to Floorp before going back. It just doesn't work as smoothly, things like tabs wouldn't save properly between sessions, pinning tabs doesn't prevent you from closing them, UI elements would disappear, etc.