I've been using the Otterbox Defender for about a year and I highly recommend it but the crappy little belt clip on the holster is another story. It's flimsy and won't fit on a duty belt. I asked for opinions in CopTalk and DaBigBR told me about the "heavy duty" clip Otterbox used to make but no longer offers.
I was able to find a "heavy duty" belt clip holster on Amazon.com and although it was for a different model phone, I was able to use a little ingenuity and replace the flimsy clip on my holster with the "heavy duty" model and that was the perfect fix. It won't come off in a foot chase or a fight. I've dropped my phone in the Otterbox a couple of times, including once on the diamondplate cabin deck of a Munson police boat and neither the phone nor the Otterbox has a scratch on it.
If your Plan “A” in a self-defense situation is to call 911 and wait to be rescued, I hope you have a really creative Plan “B.”