Use more than one.
On PC, my daily driver is Firefox Developer, patched with my CSS along with Betterfox for enhanced privacy over ArkenFox. I am an Admin and run a number of sites, so this helps.
Librewolf as general backup. Mullvad as second backup but I find that I am not the best use case for it, on top that I use different VPN services. It is for non-tech users, is not bad, just not the best tool for me but it is what I will tell people to use when using my PC since the other two have very UI minimal, heavy keyboard-centric setups. Tor for when I need more privacy/testing. Keep a copy of ungoogled Chromiu, mostly vanilla, only uBlock, again for testing and the off-chance fuzzy site but barely ever use it. They all, aside UG, sync bookmarks via Nextcloud instance so I do not need to sign into FF sync.
On Android, Mull, or CookieWeb Preview because the excellent extension management due to their pop-up window. Great for things like uBlock on medium mode, otherwise medium mode on mobile is a pajn to use, on Mull I keep it on Easy mode. Nevertheless, uBlock is a must in today's internet. Tor for when travelling abroad and do not need to sign-on to anything. Keeping extensions to a minimum. Each browser connects to different DNS services to minimise overlap, along rotating VPN servers from non-5 eyes countries as the minimum. Sounds like a lot but once you set it up, it is mostly set-and-forget.
Kiwi does extensions, too. Do not use it, though.