doesn't really matter. go with the 10 best players you can find.
key things you will want to be optimal :
mix of melee and ranged. you will want 2 capable of tanking, 1 of which with a good dps dual spec and gear. you will want 3 healers, at least 1 of which with good dps dual spec and gear. you will want a shaman. You will want something with reliable interrupts. You will want something with an MS effect. You'll want a priest and a paladin, preferably 2 pallies. Some decent blend of CC is pretty useful as well.
These are the guidlines I use to build Uld Drake runs and ToGC 10 mans.
Either play to win, or shut up and lose.