There's a fair bit to be said for WoW in and of itself, but there's some qualifications. I enjoy the game as much as I do because I play with a pretty awesome guild, and because I've purposely filtered out much of the game's metaplot (I deliberately ignore in-game stupidity, and I've long stopped reading the tie-in fiction; the last gasp of truly good storytelling in the franchise, outside of individual questlines here and there, predates the MMO). The gameplay has improved dramatically since I've started playing, ditching a lot of cruft and tediousness without sacrificing flavor (for the most part), a trend that looks to be continuing into the next expansion, at least.

It also helps if you don't take the game seriously. For all the attempts at being Epic and Dramatic, it's fundamentally a game in which I've fought and killed Bronjam, the Godfather of Souls.

Rift and SW:TOR are much more about the Serious Business sort of gameplay. I can't get past Rift's art direction, personally, but I did enjoy TOR when I played during one of the beta weekends. I'm waiting for it to get past the New MMO jitters and bugs right now, as well as for when BioWare patches in same-sex romances, before I consider picking the game up myself, though. (My wife, OTOH, would already be playing if there was a MacOS client.)