I find that MMORPG's usually end up boiling down to the same repetitive gameplay over and over. While that's fine with the twitch games of yesteryear, these days I expect something a little more. Particularly if I'm going to pay a regular subscription fee.
In the past I played Asheron's Call, EverQuest, and Anarchy Online. Actually, I jumped on that free 1-year subscription deal that AO was running in December. I played fairly steady for about a month and have played three times since. The last time was in the middle of February. Again, once you get past the first 10-15 levels of character advancement, things seem to go rapidly downhill. :/