“Brave and Firefox are two of the most secure browsers out there. Brave has made privacy its key selling point, integrating features that block ads, prevent tracking, and stop fingerprinting. Firefox, on the other hand, is the OG secure browser, challenging Chrome’s dominance for as long as we can remember. Both Firefox and Brave offer strong security, but if you’re looking for the most secure option, Firefox takes the lead.”
Ironically enough, I did not move from Brave to Firefox for the security considerations. In my case, there was an annoying UI issue creeping in, supposedly inherited from Chromium. But regardless, I did check out the Firefox privacy and security considerations and was happy with them. One feature I really like is the master password for the Firefox profile that locks and unlocks the whole browser.
The other thing I like is that Firefox still runs a fully functional uBlock Origin extension, along with its own built-in protections.
See https://www.xda-developers.com/reasons-why-use-firefox-not-brave-secure-browser