Which plays the biggest part in a game becoming memorable, its graphics, story or gameplay?

[green_sky]

Depends on the type of game.

Mario Galaxy - Gameplay and sense of joy. 
Walking Dead - Story and being emotionally played. 
Crysis 2 - Graphics. As 70% of games are graphics according to crytek.
The Last of Us - Gameplay, Characters and Story Telling (Not the story itself per say).