Firefox should definitely be used, but donating to Mozilla is a mistake. They waste a lot of it, their executive compensation rates are way too high (especially given that MoCo just laid off employees), and Mozilla still hasn't kept up with promises they gave years ago (that Pocket is still proprietary being a notable and depressing example).
Donate to smaller developers of software you use, it'll go a lot further, and they'll probably put it to better use!
Donate to smaller developers of software you use, it'll go a lot further, and they'll probably put it to better use!