For me the question is irrelevant. I don't care what the music style is, the ones I like mixing the most are the ones whose content is the most enjoyable to listen to on both performance and arrangement levels.
I'll take a great perfomance of a group of dynamic Tibetian Throat singers over a vanilla cover of my most favorite music or song any day.
Added to that, I simply don't believe in the old maxims that one must mix this way for country, that way for metal, etc. The song and the arrangement dictate the mix, not the genre. If I get a coutry song I don't automatically think before I sit down that I won't need my distortion pedal and the vocals are going to be clean up the middle, or that just because a song is metal that I am automatically going to hard pan a doubled guitar. Any monkey can do that stuff. That's not mixing at it's best.
The song has to tell/inspire the mixing engineer into what to do (assuming he gets to make at least some production decisions and isn't just a producer's prosthetic arm.). And the better the performance and arrangement of the song, the more they tell the engineer and the more inspiring they are to work with.
G.