iPhone 5- The Safe Choice. Everything is gonna be refined, tested, etc. Its nice, its fluid, its SEXAY!!!! If you don't want to mess with your phone too much to get it to your liking, go one-size-fits-all and get the iPhone 5!
HTC One X- Awesome Screen, Great Camera. Feels AMAZING in the hand. If you don't need expandable memory, and if you want a phone that has a premium feel, get this one
Galaxy S3- Very Saturated and Colurful screen. Same Processor as HTC One X, but double the RAM(2GB vs 1GB). Sleek and lightweight. OS Tweaks look irritating, IMO. Feels much bigger than the HTC, imo, though still good in the hand. Expandable Memory and removable battery!!!
I haven't used WinPho, though those who use it usually swear by it. The Nokias have great build quality, and this Lumia looks great for WinPho fans.
GSIII, if you want futureproof and a huge accessory selection.
HTC One X, if you want a good and polished feel.
iPhone 5 for the most integrated, definitely-going-to-work experience. Also a massive accessory selection.
Nokia Lumia 920. Fluidity, simplicity, and the hipster factor. And its gorgeous
I would personally get either a GS3(Android FTW!!!) or an iPhone 5, although the latter isn't nearly as impressive as the other three....