I have an OtterBox Commuter on my Droid Bionic. The thing takes a beating and looks good. I've dropped my phone several times on hardwood floors here at my house, and the phone never knew anything happened. I imagine the Defender would pretty much make an iPad like a tank. My roommate has a Griffin case on his iPhone. It doesn't look as cool as the OtterBox for one, but I'd definitely go with the OtterBox either way. Amazon has cheaper prices than the OtterBox website too, if you didn't look there. I got my case brand new for almost half price.
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"Therefore we conclude that a man is justified by faith without the deeds of the law. -Romans 3:28