How is this even a question?
The right answer is: "it depends on my mood at the time." Or, it could be, "it depends on the type of game it is."
It depends on my mood because frankly, sometimes I don't want to be bothered with a story or anything. I want to blow shit up. "Pretty" usually is more appealing than "deep" in such cases (though not always--I consider the original DOOM one of the best blowing-off-steam experiences one can have, but it's neither pretty by today's standards nor deep by any standard).
The "it depends on the type of game" gets into a whole mess of conditionals and subjectives that I don't really want to get into. Suffice to say that if a game has little or no depth, it better damn well be pretty or it's not gonna survive long, whereas a game with deep story and/or gameplay elements can get by with lesser visuals. FPS are a good example of this. They keep touting the graphics because there's not much else there. On the other hand, take the Fallout games. Kinda pathetic graphics-wise by comparison to contemporary shooters ain't they. For an even more extreme example, take Pokemon games. Yeah. I went there.