I have the leather case from Verizon. It's held up pretty well. Strong metal clip covered in leather.
The leather feels like real leather (but not high quality obviously). The velcro is pretty strong, but i wouldn't expect this to last more than 1.5 years or less.
Definitely not hard plastic, but it is stiff to hold its form, which is a good thing for slipping the phone in and out. The leather is supported internally by what feel likes strong cardboard. The inside lining feels like polyester or some other material, but it protects the screen and camera well enough.