Brave is not your friend - if they're willing to violate copyright law by secretly scraping websites and then selling the content in their AI, I'm sure they're willing to sell your data if the price is high enough (if they aren't already).
Firefox, on the other hand, has been the most trusted browser since dial-up, and is run by a non-profit. It's an easy choice for me.
Firefox is a little more complicated than that. Yes, the Mozilla Foundation is a non-profit, however it's subsidiary the Mozilla Corporation is not. It's better than Google but like all things, it's worth asking where the money comes from.
True. OP looked like s/he wanted a simple answer so I just went with the basics, especially as there's not a noticeable difference in basic browsing performance between the two in their current form (although I think FF is slightly faster right now).
Brave is open source. You can review and compile from source if you have privacy concerns.
To be completely fair, Mozilla is no angel. They installed extensions in people’s browsers without asking for permission, for example. No thanks.
Librewolf is my recommended go-to from a privacy perspective. And Brave is not horrible. If you look at Brave the company, they aren’t any worse than Mozilla the company.
And if you look at privacy features from a purely test driven point of view, Brave is better than Firefox, and Librewolf is better than both.
Finally someone that is being objective here!
If I had to suggest a browser to a non techie person I'd definitely tell them to use Brave since it's the best middle ground between full privacy to the point of clunkiness and, well... Chrome.
It is still a little invasive by shoving features/ads in your face (wallet, videoconferencing web app, sponsored backgrounds, etc.), but they're less armful than other options and easier to turn off than slightly obscure about:config settings that break the experience of a non privacy concious user