I have worked in Telecom for many years (and still do), and my money will go to the Nokia Lumia 920. Absolutely superior. The new Windows Phone software shows that Microsoft have finally learned their lesson and will truly innovate on things that can improve the customer experience...

But if you are still set on either iPhone 5 or S3, I say watch this ad :)
http://www.youtube.com/watch?v=nf5-Prx19ZM&feature=share