Samsung Galaxy S3. Better and bigger Super AMOLED screen, better camera options (burst shot mode and HDR), NFC and buttery smooth with no lag.
You'll love the SGS3's Super AMOLED screen because it has the best contrast ratios out of all smartphones. The black levels are amazing and the colors are pleasurable to look at.
The iPhone 5 is loaded with so many bugs and lag. Apple stuffed up with iOS 6 which basically makes Apple maps and navigation buggy and unusable. The locations given by Apple maps are inaccurate.
The camera of the iPhone 5 also has many issues like the purple tinge problem.