I went to Radio Shack today and picked up the Otterbox Commuter. Last night I was at Verizon and bought the Incipio because I went to the Radio Shack by me and they didn't have the Otterbox. I am taking back the Incipio for various reasons, one of them mentioned above it covers the notification light. Another reason is the Incipio has nothing to cover the USB, HDMI and headphone jacks, where as the Otterbox does. The Otterbox is a much sturdier case and much better designed, which is something I figured out with my OG Droid after various other cheap cases.
I did look at the Otterbox Defender while I was at Verizon, one thing I am sure of is if you have that case on your phone you could throw it against a brick wall and not damage it. However it is HUGE. With the included belt holster it is like strapping a flat panel TV to your belt. Just way too big, I like the protection but the Commuter protected my OG for almost a year and a half. My OG is in like new condition and I wear it on my belt and work as a automotive tech, not exactly a friendly environment.
My opinion get the Commuter and forget about it, its protected.