I've used the Defender since my first iPhone 3G. When it was 2 years old, I still managed to sell it for $250 because it was in immaculate condition, thanks to my Defender! I have only used Otterbox with my iPhones, and I wouldn't trust anything else to protect it the same way!
After owning my iPhone 4 for two and a half months, it still doesn't have a single scratch on it. I work construction, so trust me, it goes through the worst conditions possible!
So sorry to hear about your misfortune with the Defender....