Lost Planet mission 7 for me. I actually found that level to be more impressive than Gears. There is a huge snow plain and quite a lot of very big enemies can spawn. If you don't kill them you end up with an incredibly impressive scene of huge bugs and men all walking around with explosions going off everywhere. Looks amazing.
I also had another minor one with Just Cause. Tbh I don't understand why that game wasn't more hyped. Graphically I think it is amazing. Skydiving from an extreme height, then landing on a speedboat and going insanely fast over the great looking terrain. Simply very impressive.







