I'm just going to make it easy, there's currently 3 Free to Play Games that i'd say is top quality and worth a look
1. LOTRO
-best graphics of all these games
-amazing lore
Watch:
http://www.youtube.com/watch?v=gH__9NMDa-M
2. DDO
-got a more actiony feel and really well done questing/adventure system that is alot more than "kill 50 rats or pick up 30 hides" .
-good old Dungeons and Dragons system [if you remember Baldur's Gate etc, then all the rather hardcore mechanics would be familiar]
Watch:
http://www.youtube.com/watch?v=rHeYfrjRV6g&feature=channel
3. Everquest 2 : Extended
-huge world , huge amounts of quests, huge amount of classes/races and options. this game launched same time as WoW so it's pretty old but it got an insane amount of content.
Watch:
http://www.youtube.com/watch?v=mlQcdcf19y4&feature=related
That's the 3 i've played, i tried Allods which felt a bit too much like WoW [which might not be bad thing for some] and Rune of Magic , never tried.