If you like story content, Star Wars the Old Republic and The Secret World are the strongest in that field, imo. There are Dungeons, raids and the usual mmo features, but the selling point is the narrative. Perfect for the solo, casual gamer with limited play time.

Rift if you like WoW in a different setting, last I played it had far more features than any other MMO's out there.

GW 2 if you like a dynamic world where the world evolves due to the player actions. There is a narrative, but the "quests" are handled differently.