Mint.

I switched a friend from Ubuntu to Fedora specifically because the partition setup during Fedora install is so good. (It was during a new build)

You can donate to Mozilla, and I do. https://donate.mozilla.org/en-GB/

A lot of people will have to donate a lot to equal the amount they are getting from Google though, and if Google pulls that money I feel that Firefox would end before people donate enough to make up the shortfall.