Multi-plat comparisons are only a demonstration of which console is easier to develop for and/or which one is the lead platform for most projects. The way to compare their relative graphical prowess is looking at their exclusives.
From a purely graphical standpoint: (imho)
MGS4>GT5:P>Uncharted>Gears>Mass Effect
Not trying to be a fanboy. Of course, it's hard when you own the best console eve... dang it