What is the best iPhone 5 case for running?

I just got my first iPhone (iPhone 5) and want to go running with it, but I'm concern about a case that will result in my phone being covered in sweat and possible damage.

What is the bast case(s) so that it stays dry on long runs in the heat (15-20 miles)?

Added (1). I forgot that I also want a case that will allow me to plug in headphones to listen while I run.

A light plastic or rubber case. Light because you don't want it to weight down your shorts. Rubber will grip to the inside of pockets. And for the love of god get a good screen protector. If it somehow falls and lands on the screen it MIGHT just save it. Or maybe look into an arm strap. You know so you can Velcro it around your arm.