I normally get Seidio cases. They are form fitting and pop in and out of the belt holster with a rocking motion. You put the phone into the bottom of the holster and then snap to top against your hip to lock it in place. It does protect you phone very well, I have dropped it (sigh,,,) and only the case has a small mark on it, the phone is still perfect. Seidio also makes cases for extended batteries.
The only problem I have with it, is it can be a little hard to remove for a battery pull.