From :gameogre.com

Top MMORPGs are ranked based on several factors and some are entirely objective. The deciding factors include popularity, playability, expansions, value for the monthly subscription, and community support. Pay-to-play and free MMORPGs are ranked separately.

1. Guild Wars – Game Lair – Excellent MMORPG that can be bought in stores, but does not have any monthly fees. Will likely be a leader of the Free MMORPG (no subscription fees) genre for years to come.
2. RuneScape – Game Lair – Most players either love it or hate it. Continues to gain popularity with MMORPGers on a budget despite having its share of critics. RuneScape has improved its graphics considerably with the high detail (HD) version.
3. Maple Story – One of the few MMOs that looks like a console game. This game has no races but each of MS’s 4 classes has their own specially-themed city.
4. Perfect World – Boasts a giant game world and less grinding due to the huge number of quests.
5. Sword of the New World – One of the most innovative MMOs in years. Players can control 3 characters at once and all the characters of a player are a family. In addition, sports some of the best looking graphics in the genre.
6. FlyFF – Fun cartoonish game with a theme that revolves around characters flying.
7. Rappelz – One of the best looking freebies with an extensive pet system.
8. Silkroad Online – Solid Fantasy MMO with a great historical theme.
9. Dungeon Runners – Similar game to the Diablo games, and, to a lesser extent World of Warcraft. Great game to play for a few minutes. Offers a humorous take on the genre.
10. Magic World Online – Ambitious free game with such innovative features as video chat, players being able to design and build their own houses, growing weapons, and an official in-game bot that helps with grinding.

Source: GameOgre.com