Tales of Pirates Online. I have been playing on and off for a while now, and it is great. It is constantly being updated, the community is great (even though a good portion doesn't speak English), the graphics are okay (they aren't anything stellar, but they suffice), and there are many quests. Of course, gameplay is another factor and it doesn't disappoint. I am one to constantly get bored with an MMO because gameplay gets too repetitive, and I have always come back to Tales of Pirates because somehing new is usually there when I return.
You could also try Kingdom of Loathing if you are interested into command-driven MMOs. KoL is a little easier, since you don't have to have a thesaurus of commands sitting next to you while you play, you only need to click on the action you want. The game is really funny, too. For example, two classes are Accordian Thief and Disco Bandit. The community is generally good, just don't go in acting like a n00b and you'll be fine. You are allowed (as far as I remember) to have more than one account, so long as you don't abuse it. When you reach the final point of the game, you can "ascend" to a different class while you keep one skill you have learned in your previous class. Lots of replay value, here. You can even have your own store to sell stuff with. Now, when I played, the userbase for KoL was relatively small, so I am not sure how big it is now.
