I did a review of the Luvvitt Crystal Case for iPhone 5, which should work on the 5s. I didn't love it. No pun intended. I haven't seen or reviewed a crystal case that I love. I should note that I'm difficult to please, at least when it comes to iPhone cases.
I'm deciding between the Spigen and the Moshi clear cases. Both look good and get good reviews. And for me, most importantly, minimalistic cases. Also considering putting a front and back shield on, instead of using a case. ahhh, decisions, decisions