That's what I use and I love it. It not only has a clip on the back but also 2 loops that you can put your belt through so that it absolutely will not fall off. The last one I had a while back just had a clip on the back and sometimes if you were kneeling or bending funny it would pop off.
I use the iPhone Smart Case made by Waterfield Design and love it. It has many different color options and it also gives you a couple different size options (bumper or no bumper). I used to go through cases like crazy trying to find one that clips to my pocket without falling off or getting in the way or loosing my phone and since I've tried this one I haven't even thought of trying anything else.
We got the ones sized for a bumper, which allows you to put your phone in there with random bumpers or cases on it - my daughter has a plastic case that covers the back and sides of her phone and has this huge concho on it and it fits in there just fine, I use random bumpers and cases that cover the sides and back. We've never had it fall off (some clips just don't stay on your pocket), or any problems with it. It is pretty durable and has a little pocket if you want to throw headphones or money in it. And their customer services is great, I've got a few other items from there and love their stuff.