iPhone case

That would be up to you. I carry my 5S in a leather sleeve case. That is my preference. Most of the decision has to do with what you use your phone for, how often it is in and out of your pocket, is it in a pocket with other things that could scratch it. Think about it.

Hands down, I love the OtterBox for all of my Apple product cases: http://amzn.to/299BFCf

I agree. The Otterbox iPhone cases cost a little more but well worth it for the safety.