One of my first thoughts was: could either survive the extreme tests that manufacturers and consumer sites love to throw at such products? Could you drive your car over one and still make a phone call? Could either absorb a smash from a 10-pound sledgehammer and still offer up Angry Birds?
But I'm not going for silly--or for hype.
These cases are actually designed to offer elite protection in everyday use. They give you peace of mind if you drop your iPhone, expose its surface to liquid, fall and land on it, etc. They're not for use in strong-man tests at your county fair.
For sensible uses, both the Ballistic HC and the Griffin Survivor more than suffice.
That said, which do I prefer? Both offer multiple levels of protection, including a main plastic case, a protective screen, a rubberized outer covering and a carrying clip. Both are impact ready and wrap the phone up tight. They cover all ports and connectors. They're similarly priced.
They seem interchangeable at first, but the devil is in their individual weaknesses.
The Ballistic HC uses a face-covering outer plastic shell with its clip to offer a fourth level of protection. But this also makes the phone more bulky and covers the screen, preventing quick glances at your device. Also, the facing forward "Facetime" camera is covered by a plastic film that became so worn and dirty on the test version that images became unidentifiable.
As for the Survivor, it feels meatier in the hand because its rubber layer is thicker. Its clip is smaller and detachable to allow for charging and syncing. But it has a thick, annoying rubber tab covering the main camera that is so hard to pry open, you're likely to miss spur-of-the-moment shots.
So between the two, it's your call. If you prefer maximum invulnerability, I recommend the Survivor. If you want easiest, uninterrupted functionality, go with the Ballistic.
And if you want to hit something with a sledgehammer, grab a watermelon and play Gallagher.