Gameplay is always an important part, and story is as well. Games with a good story can be interesting, intriguing, and such. Graphics are mainly for immersing the player in the game, so they can create different moods: cheery, frightening, and such. You wouldn't want difficult-to-learn and hard to remember controls, so that along with graphics aren't incredibly important. Heck, just as long as I know what it's trying to get across, I could care less about the graphics in a game.
I say gameplay/story are most important.