Man, you're gonna hate me.......but......for all of the choices, it just depends. If recorded and mixed stereo lead vocals.....mono drums, keys, etc. It just depends what the music (and client) is trying to say. Everything is everything.....I know that sucks, but the cliche is true. It just depends. You have to be open minded, and the only expectation you need is the committment to doing whatever to make it as compelling and excellent as you can. Sorry.