I've played many MMOs over the years (EQ1, 2, DAoC, AO, SW:TOR, Rift, Star Trek, Conan, GW:2...) and I always come back to WoW. I'll admit I thought the Panda stuff was silly at first but I got over it and actually enjoy it. I actually like the graphics in this game because they aren't so intense that they affect gameplay.
Last year this time I was
hardcore SW:TOR. The one thing that really bothered me was the damned gameplay. It was so laggy, the actions were that is. I also had to decrease all my settings to lowest everything to get 'decent' playability. I'd read about people with mega-gaming rigs that had problems running it. Felt like I was playing through jello or wading through mud. We even had to time our jump for those damned datacrons. The tip was to hit spacebar about .5 seconds before you'd ACTUALLY hit the space bar. Yeah, it was bad. It wore me down and I stopped it and all MMOs for a time.
Fast foward to Mists Beta and I was back at it. The smooth gameplay is just second to none. I also have friends I play with and that's a definite plus.
I've yet to play an MMO that has the smooth play of WoW ( closest was GW:2 but they nerfed my class!

). That's my baseline standard for an MMO: how smooth is the play? If your game looks like real life but plays like crap then I could care less.