Best 5 man comp for endgame BiS gearing

[Madsage]

I think that bear is a great choice if you are playing with 3 mages, with Improved Thorns and Demo Roar your bear will generate aggro faster then a warrior on melee mobs and your mages with Ice Barrier will soak up spell damage from casters while spamming arcane explosion which counteracts the lack of mitigation compared to a warrior and spreads out damage making your Prayer of Healing even better.

If you have a paladin healer warlocks work too, since you can start pulling with Retribution aura and switch to Concentration aura when you use Hellfire.