Slayer: Offensive/soloing MC
Death Knight: Defensive/Raid/Main Tank MC
Heroic Were-Hunter: Offensive/soloing MC
Savage (Troll Only): Offensive/soloing MC but can be used for Defensive/Raid/Main Tank MC
Juggernaut (Ogre Only): Defensive/Raid/Main Tank MC
thats just a quick break down of each MC and what they are used for. None is better, just different uses.