Graphics advancements tend to occur naturally over time, once a game comes out that advances to a new level of graphics, it's hard to go back more than one step in the name of gameplay without thinking "nice game to play, but the graphics suck"... see ArmA, I bought this game because I really enjoyed Flashpoint, but just couldn't play a game with 4 years old graphics
so personally, gameplay comes first with graphics very close behind, I'm not hugely fussed on a "great" story as long as the game is fun to play (I hate unskippable cutscenes, if I want to watch a movie I'll go watch a movie, I'm here to shoot stuff dammit), if the story unfolds as part of the gameplay then all the better (MaxPayne had fantastic gameplay as well as a good story but equally I'll happily play a game with virtually no story to it)
I can't say I pay a huge amount of attention to sound, it's been very good for quite a long time now, I don't really see how they can improve it much beyond it's current state.