What is more important to you, what keeps you interested?
Do you like so called "walking simulators", where you do not much more than walking around experiencing some story? Or do you stay interested doing some stuff is there is no story at all giving any meaning to your actions?
I know it depends a bit on the genre you are playing... a racing game is something different than a RPG. But generally speaking... what do you enjoy more?
You can't really break games down into those two categories.
My favorite video game of all time is Silent Hill 2, and depending on what you call "gameplay" it can be thought of as extremely bad or extremely good. Combat wise, it's quite bad. The controls and camera are very out dated, most enemies are quite easy, and there is very little room for skill involved with the game. However the game incorporates an element that no other game has really come close to mastering like Silent Hill as done, and that's the element of true psychological horror. It makes the player feel anxious, uncomfortable, paranoid, and hopeless. The setting and mood of Silent Hill is what makes the game so fantastic. It's also a unique game that not everyone will enjoy.
If the story is bad and the graphics are good it's not fun. If the story is amazing but the graphics are meh, it could be okay but it's mostly likely not fun once more. A perfect balance of both in my opinion would be Witcher 3 for Xbox one. But it's my opinion he's I love that game
I don't consider myself a gamer. I am a translator and an editor, so for me the storyline is the reason I buy a game. I'm still in love with Skyrim. It feels like it has been adapted from an actual novel, not from a script written specifically for the game.
A game doesn't need a story if it has the right mechanics and ambience... But if it's your typical AAA game where 90% of the focus is on top end graphics then the story is everything... I prefer repayable games that make me think strategic and solve puzzles...