1. World of Warcraft Cataclysm (Masterpiece. You SHOULD play it. period)
2. Rift (most polished MMO after Wow. it earned its 2nd place by combining all others' MMOs' characteristics like WoW's Talents and BGs . GORGEOUS visuals. surpassing the visuals of Aion also playable in low-end machines)
3. Warhammer Online ( The RvR realm vs realm is fucking awesome. and thats combined with excellent pvp balance and fights makes this 3rd in my list)
4. EVE Online ( oh god you HAVE to try this game out. the 1st week is enjoyable . the rest are a blast! the player-controlled corporations and game economy is awesome. also the graphics are FCKIN FCK FCK!!!! GREAT!. the combat is good also. along with trade ships and wormhole jumping!
5. Lord of the Rings Online (its just a plain good MMO. not much to say here. its F2P! also has a big player community)
The rest mmorpg's not worth your time
Aion: Grinding game from beginning to endgame. PvP outbalanced like shit. Instances too easy. PvP gear are essentially grinding all day in instances to get them. no PvP is encouraged. only PvE carebearing.\
Star Wars The Old Republic : played the beta and I have to say the game is not fun at all. I just didn't like anything about this game . Maybe its just me . maybe not. we have to wait for the 1st gamesites reviews. But whatever their reviews say. I'm not wasting money to this broken mess which bioware calls an MMO.