Alright, after pondering and while i think theres many variables and its not a clear cut answer but a conglomerate of aspects that make a game worth playing, i would have to say story.
Gameplay by itself getsme playing a game for fun, and while it is fun it wears out fairly fast. For example a 2D fighter. It has great gameplay and i love it, but i eventually get tired of it. What drives me to play these games longer? The story. the story drives the gameplay forward and extends its momentum.
Yes gameplay gives the game more replayability than story does, but without that first push, i find it difficult to play the game for anything longer than short bursts.
With that said, given the Poll gives the option of good story with bad gameplay, it doesnt sound like something i would play, and something with good gameplay and no story would be something i would play for a short time. Between those options the gameplay one would make more sense, though if the story was truly amazing i could probably live with the bad gameplay. It woudl all depend on how bad it actually would be.
So err... im still not answering the poll, but thats my opinion.