FFXI is a lot slower to grind than WOW. I just want to warn you there. It takes FOREVER to level it seems also. Other than that ...a fun game with a larger area than WOW it seems. Or maybe that's because you can't have your own chocobo (or you couldn't when I played.) Hmm.
Guild Wars is the only one I play. None of the others have been worth paying for to me.
Used to play DAoC as well. Started on Ultima Online. Unfortunately everything after has been heavily based on UO or EQ (except for EVE I suppose) Same boring shit in a prettier new package.
It'll take something truly unique (more skill based than level grinding for one) before I decide to P2P again.
True Fantasy Live Online for Xbox looked badass, until it got cancelled
Ultima Online was the best mmo back in its glory days, but now its ghey.
Asherons Call 2 was pretty fun in beta, me and Shade got fond memories of "gokarts" and "atoyats".