Group comps and leveling

[Apatheist]

If I were going to stick to 2 boxes I'd go with a fury/prot spec warrior plus a paladin or shaman healer. Warriors are beasts for PvE and PvP if they have a healbot keeping them alive and finding 3 DPS to fill a group should be easy. You can pick which classes to bring so they don't compete for your loot.

By the way, if you have an efficient AE setup leveling in dungeons is actually very fast. A warrior/paladin, any healer plus 3x warlock/mage clears dungeons very quickly. I've already done the math elsewhere here but grinding dungeons is faster xp/hour than questing.