I havent played all of 'em but i like runescape... mainly because it is a lot of fun if you are in a cool clan like 'the'
I agree, if you want a good game, buy one. The free ones get quite boring. Barely have quests and have the need to grind many levels. Played Silkroad - Got bored the first hour. Played Rappelz - Got bored the first hour. Played RuneScape - Decent for a month or so. Played Maplestory - Had fun for about a week. Played Knight Online - Fun 'til level 30. Easily done in 1-2 days. Haven't tried Ghost Online, maybe I will. Played World of Warcraft - Fun on a long term basis (Pay-To-Play) Played Lord of the Rings Online: Shadow of Angmar - Upon release, it will be good on a long term basis (Pay-to-play) Played Guild Wars - Fun for a year. Been drifting from it, probably gonna start it back up and complete Night Fall soon. (1 Time Payment) So basically, if you want a good game, buy one, unless you want countless hours of grinding to level.
I suggest Flyff. If anyone remembers the ROSE online game when it was free, it's pretty much a little bit "less good" version of ROSE, except its free forever.
Get the new LotR one if your comp. can handle it. It's P2P but if you preorder some special version, you don't have to pay the subscription. Downside is that version is $200.