Star Wars Galaxies: This one was my first MMO, and I loved it. But, everything went to a hole after 11/5/05.
Everquest 2: I love this one, the game mechanics make it impossible to solo play which I don't like. However, is so rich in lore and there are many possibilities to RP.
EVE: This one is unique, and one of the best games I have ever played. Of course, is not easy.
City of Heroes/City of Villains: This one was fun fer the first 10 levels then it turns into a very repetitive game and it bored me.
World of Warcraft: It doesn't have the best graphics, but I have had a lot of fun times with this one. Combat is one of the best for soloing.
Vanguard Online: This one was looking great in beta. Then it jumped off the precipice.
Pirates of the Burning Sea: Haven't played it and don't plan to.
Tabula Rasa: See PotBS.
Lord of the Rings: I will play it, a bit later. We know it has a lot of lore to play with, many opportunities to RP.
Sword of the New World: This one is one of the best, fast action, similar to Diablo and Titan Quest game play but with a party of three characters. Thanks to having a party, it was solo able. I like this game a lot.
From my opinion, the one that fail was Star Was Galaxies.