I find funnier the challenging comps: Rogue/Mage or Warlock, Rogue/Hunter (pretty hard comps but really satisfying when u nail it), Arms/Ret, Arms/WW, Ret/Warlock, Ret/Hunter, Ret/Rogue... (off heals + DPS)
I love RShaman and Disc, but I feel they are too strong, I still have fun winning mirror...