The best way to choose a handset is to touch it for real and see how it feels like. I suggest you go to a store and try some devices. Hold them, try the responsiveness. You can ask a personnel for assistance.
As for the operating system - it doesn't really matter if you choose iOS, Android or Windows Mobile - they are all fancy and touchy and have similar features (just stay away from cheep Chinese no-name handsets). HTC, Samsung, LG are fine.
I personally use Android HTC and I like it. Good luck!