I play and have always played WoW.
-Tried AION. I really enjoyed it through the beta but was so disheartened when my characters got deleted when it went live that i gave up on it.
-Tried FFXI. That game is far too unfriendly. I tried talking to people and all i got was either Japanese text or 'i don't talk English' from the auto-translator, not helpful on a game where you practically can't advance without the help of other people.
-Tried LOTRO. I found it to be very 'meh', but then i'm not a big Tolkien fan to begin with.
-Tried Guild Wars. Didn't like the cap at 20.
-Tried Champions Online. Too easy to gimp yourself if you don't spec right, but with credit to the game world it is fairly amusing, particularly the PVP but again as long as you don't gimp yourself and people don't use cheap tactics like burrowing or flying away.
-Tried Age of Conan. That game is, unbelievably still buggy as hell for me. And if you go on a PVP server, prepare to truly know the meaning of the word 'griefed'. Oh, and some talent trees are still FUBAR'd. I can't count the amount of times my 60-something Necro got his gameplay mechanics completely rehauled.
-Tried EVE online. Slow, dull, mundane. Avoid.
I would love to try APB, when i can afford it. A shooter-based MMO is my sort of thing, though i do understand it's light on content. Still, i've always enjoyed the cops n' robbers thing so i would like to give it a go.