Interesting story is what I voted for but I'm a believer you can't shelf any of those. In the same vein of games being art they contain a lot of art. Most of my purchases are based on which games have the most artistic merit. Visual, musical, narrative, or otherwise, I favor things that are different.
The reason I didn't vote graphics is because that caries a stigma where it is assumed to mean realism, and I disagree that realism has any correlation on how good graphics are (Folklore > Killzone 2 in my opinion, for example) but also because as I mentioned, there is more then just visual art in gaming.
But despite my heavy influence by art as a game, game play is still a high factor on whether it's enjoyable. See Mirror's Edge for great aesthetic promising concept but being more frustrating then fun later on, but I knew that before I bought it.