Re: Which Game has the best SFF story?
Baldur's Gate series
Mass Effect series (since it little more than an interactive movie, with you guiding the camera)
Neverwinter Nights 1 and 2 (won't call them a series, since the two stories have almost no links apart from peripheral NPCs)
Dragon Age: Origins
((i think its obvious that i'm a huge fan of virtually everything that BioWare produces))
Lord of the Rings Online has in incredibly rich story (if you follow the Epic quest chain), far far richer than any other MMO.