I think you should look at Firefox as the product that it is and not let the politics influence your decision too much. It is true that Mozilla’s management has been terrible over the last few years, and it shows, but as of today Firefox still is a browser that is kept up to date, can be customized extensively, supports a wide variety of extensions and has a large community behind it.
Personally, I use several browsers for different purposes because that works for me to stay organized and compartmentalize my activity. Firefox is one of them and I have no intention of replacing it.
I’ve been using Vivaldi and Ungoogled Chromium for a while and I’m quite happy with them. Brave is not my cup of tea although it has a decent privacy defaults. I haven’t used Tor Browser that much but is also a great choice specially as speeds are improving everywhere.