PC is best because it shows the whole boxart.
after that comes the new one PS3, old one was garbage i couldn't stand looking at it,it made a lot of games look crappy, mainly because of the fake gloss.
After it comes Wii, because its simple and small.
last comes 360 because is too green, and green (unlike black and white) doesn't fit all games you see a dark looking boxart with flashy green on it makes it look like a launch box, i think the kinect cases are blue which is better IMO.
Also if you don't mind, i'll give my opinions on the boxs themselves
PS3 is transparent , which is both good and bad, good because its transparent which is cool and new, its also pretty sturdy,but bad because it can collect finger marks and it have a dirty glass look, you can clean it however.
360 looks vibrant its kinda transparent but pretty cool color , a little less sturdier than the PS3 one however
Wii is sadly the most flumsy looking out of three, the white isn't good looking, they didn't bother with the box much i think, the box itself feels almost like a plastic-ish paper, its very fragile.