Brave is already at 60+ million MAU. It's already 1/4 of the market share from Firefox. Brave's market share is rising, Firefox is declining.
If there is one horse to bet here, it is Brave. Sticking with Firefox is just playing "controlled opposition" right now.
Attempting to convert Firefox users is not a long term strategy, and doesn't do as much or anything to create a better web.
I like Vivaldi on mobile with built in adblocking and some bit of control for text size (aging has not been kind to my eyes, mobile text is too small most of the time). Vivaldi hasn't made it pass evaluation stage on desktop for me as it often crashes when I try it (linux distros). (ed: tried it years before)
Browsers are going to continue to be a central part of our OS -- no stopping that. I hope the companies can be taken to task for colluding and that innovation is not stifled.
I happily use Vivaldi on Linux Mint for more than two years without any issues!?
The last time I evaluated it in Fedora (maybe 3 years now?) it was crashing under moderate use, and haven't had time to check recently. Perhaps when some time clears up I should give it another go.
I'm currently using Edge with uBlock Origin Lite. I can't tell the difference between uBO and uBOL. AdGuard MV3 also seems to work fine but I've used uBO so long that I'm sticking to it out of comfort.
That said, I keep Tor installed for as close to perfect privacy as possible. It feels academic though, as everything I do is pretty pedestrian and I generally avoid Google's services. I do prefer Edge to Brave, there's many features that I like here, but it's my backup plan if somehow Edge's adblocking doesn't work as well as it does today.
Even though I don't use it daily, I promote Brave to anyone that would normally be inclined to use Firefox. Otherwise, I push native browsers for all the inherent advantages they have. For me that's Safari on iOS and Edge on Windows. There's no doubt that built-in adblockers like Brave has is the future, they're just ahead of everyone in many ways. For me, Brave is what Firefox should be by now, in all regards.
Now you don't have to abandon Firefox because of their dumb UI decisions anymore.
It would be nice to see innovation in this space but web standards implementation requirements may make that bar too high? I'm not a browser dev, just an armchair techie.