well as a genre no, most are pathetic attempts at making a real game
even some that put effort in can be bad, I recently played the EVE online free demo of steam, that's pretty rubbish.
I did enjoy WoW for a while, but then it became dull as solo play dwindled in favour of 4 hour long dungeons, which I either never had enough time to finish, or would end up grouped with a bunch of morons, or my server would crash.
So no