Brave is based on Google's Chromium codebase. In contrast, FireFox forms the basis for the Tor browser relentlessly scanned by security researchers worldwide. There's no contest.
I'm sure that in terms of privacy you're totally right, but out of the box the adblocking built into brave is really nice. I think it deserves some representation at least.
I flipped back and forth between Chrome and Firefox forever, Brave was the first one that made me delete my shortcuts for both. Knocks the competition out of the park