I found
WoW to be one of the least entertaining of most MMO's mainly because of the poor quests for low levels being repetitive and boring.
It has its up's at High levels which is why its best to kind of learn as Much as you can in the 30days when you buy the game then bugger off to Servers
Lineage i must say is fun, it just lacks the Pvp system that
WoW has.
Strangely enough, i probably will get flamed by haters, but the only game i really actually found was quite satisfying to play was a Small game called Tibia, like most MMO's it is a grind feast, but it has some decent quests and the satisfaction of killing some random person at a totally random time is just great.
Also it has that really negative effect that most MMO's don't have, for example in
WoW when you die, you don't really lose much just some exp, but nothing serious where on Tibia if you died, it could set you back a day or more this could be taken as a bad aspect but for me its one great aspect as it gives the game that nice bit of challange.
In saying all that, i actually now don't play MMO's anymore.
Iv grown bored of them, playing them for so long now, turning on an MMO i have never played is like turning on an MMO i know so well, because there is nothing Massively different between them anymore.