When you look for comparisons between products, look for one that is done by a non-biased neutral organization, third party at minimum. Not from the company making the product hence have an incentive to paint them better than its competitor.
You can make a stronger point if you go and verify each claim in the comparsion chart and proving Brave is actually better than Firefox. Instead of just linking a comparison blog from Brave. Don’t trust, verify.
And a matter of fact, privacy is only a part of what a browser should have. Not a complete feature set. I can make an extra private browser that only accepts my custom protocol and only with my websites but that would be not useful as a general browser one wants to daily drive, which is what Firefox aiming to do.