FUNCTIONAL graphics are important, the game doesn't have to look stunning but that's not an excuse for it to look like arse.
That being said, I would happily play Total War: Rome II in the diplomatic window and fight the battles with the strategic view only. Sure it's nice to see troops mashing into each other, screams of the slain and the whistling of projectiles but I'm more concerned with commanding an army to flank my opponent. The mechanics are far more important than the graphics when you've got the basics down.
The graphics just need to complement the gameplay, not supplement it.
Therefore gameplay is most important? but graphics impact upon gameplay if they are poor.
That being said, I would happily play Total War: Rome II in the diplomatic window and fight the battles with the strategic view only. Sure it's nice to see troops mashing into each other, screams of the slain and the whistling of projectiles but I'm more concerned with commanding an army to flank my opponent. The mechanics are far more important than the graphics when you've got the basics down.
The graphics just need to complement the gameplay, not supplement it.
Therefore gameplay is most important? but graphics impact upon gameplay if they are poor.