Gameplay (for obvious reasons)
Storytelling (games can have magnificient storytelling, even if the stories aren't all that great, and I love games with good storytelling)
Visuals (If by graphics you mean technical prowess, then replace this point with something else. A greatlooking game doesn't have to be technologically advanced at all though.)
Above all comes immersion though, but I can't have immersion if any of the above are subpar.