While the iPhone 5 doesn't interest me, I can't get behind the S3 either. TouchWiz just isn't for me.
Personally, I can't go with anything other than stock Android.
Now it's just up to Google and whoever they get this year to deliver something worthwhile. The Nexus line could be so much more, and in my opinion, Google holds back. Not to mention they haven't had one good launch so far.
The way they handled the Nexus 7 gives me hope for the Nexus 2012 phone. Time will tell.
So, for me, it's a pass on both the iP5 and S3.