Gameplay, of course. I don't care if the game has no story (SMG), but if the gameplay's great, then I'm sold. However, I would still buy a game if its story seemed very compelling, thankfully most of those games seem to have good game mechanics to go along with the story.
3DS FC: 1306 6473 7511
Nintendod Network ID: xsorenx
Add me for Pokemon, New Leaf, and Fire Emblem, Mario Kart 8.