At this time I have Mabinogi and Megami Tensei IMAGINE on my harddrive. Mabinogi tends to get boring quickly, but there's supposed to be a big update in March, so I'm hanging on to it. I just started Megami and so far it's pretty cool, no telling how long that appeal'll last though.
I guess what makes me like those games is how the combat system is based less on simply overpowering your opponents by mashing the skill buttons, and more on rendering them unable to deal a hit on you, by using the right skill in the right situation. Plus with Megami it's nice to have a MMORPG that's isn't set in either a medieval fantasy world, or the 31st century.