I've purchased a number of different cases, but one that I happen to like when I want more protection is the Qmadix case.
Dual layer, but the two layers don't separate. I used this while skiing, and it worked great! TPU inside, with a strong plastic shell on the outside. Easy to gripe, and the covered volume/power buttons are easy to access.
Guess it's a matter of taste... $28 on DayDeal