Played UO off and on since 97 until last year, EQ for a few months when I only had dialup and UO was too slow, then AO for a few months, then Beta tested AC2 and SWG, then played DAOC for a couple years, then played SB for almost a year, then beta'd CoH, then beta'd WoW.
But at this point the genre is stale for jaded vets like me. No developers are doing anything different besides changing/refining the window dressing. For someone new to MMOs, you must be like a kid in a candy store like all the wide-eyed goobers who are spazzing over WoW like it's something other than a direct clone of DAOC.
It's a bad time to get into MMORPGs. What you'll be playing right now is a bunch of formulaic and boring level-grinding faux-"PvP end game" games. What you want to do is build yourself a time machine and go back to 1998 and play UO. That was a triumphant era for a then beautiful game before EA bought Origin and proceeded to systematically destroy the game.
Either build a time machine or wait for 3+ years when the EQ clone MMORPG market is completely saturated and it becomes profittable for someone to make a 3D UO97 clone. Then you'll have a game worth wasting your time on.