I think that plot and good gameplay is much more important that graphics in the kind of games I do like, but this is not true in any kind of games.
IMHO Gameplay come always first, a game must be fun to play, then came the rest in an order depending on the game kind, as an example an online fps doesn't really need a plot.
Anyway it is also difficult to describe what "good graphics" means.
Saying that "good graphics" means high-resolution and photo realism is like saying that a photo is better that a painting.
It's not a matter of pixel, is something more complex, it's a form art, you have to choose your canvas, and you have to use it well.
An example is Okami (wii and original ps2 version), its low-resolution/low definition graphics to me is the most beautiful eye experience I had from a videogame. The plot and the game-play are just as beautiful, so to me is one of the best game ever.
Anyway It's a matter of taste ;)