360: Halo 4.
I wouldn't say it legitimately "pushes the hardware" the most of any 360 title, that award likely goes to GTAV, but it makes far better use of what it does use than any other. I'd say that's more important than raw power usage. For me personally it's the best looking 7th gen FPS (overall better than even KZ3 and C3).
Wii: Honestly no idea. I can think of multiple Wii titles that looked good relative to the hardware, but there isn't a specific one that really stands out to me.
PS3: GT6.
Tech wise this is the holy grail of the 7th gen. Many of us complain about how GT6 should have been a PS4 title, and it seems PD half agree with us. It's pretty obvious GT6 was made with the next gen transition in mind. To quote DF "we're seeing state-of-the-art features that aren't even present in the next-gen Forza Motorsports 5."
