Hard to answer. I think the iPhone 5 has a better design but I actually like it's design less if that makes sense?
I'm just tired of the iPhone 4-eqse look were've had for the past like 3 years. Not to mention the iOS UI also feels dated and has been more or less the same since the original iPhone. GS3 feels fresher, I wish the old teardrop iPhone rumors were true
Also, both look tragic compared to Nokia's 920.