I don't know if you can rate either as really edible on the pizza scale. However, I've only had CPK once, so I can't recall HOW bad it was, just remember it was bad enough that I never needed to make that mistake again. Had the same experience at Olive Garden when I was in the middle of nowhere California one night. Will never do that again.
Worst pizza I've had is too tough to call. One that stands out was in some tiny town in Michigan visiting a buddy. They claimed it was Detroit Style, which at that time I had heard about but never had. Unfortunately it just tasted like grease on casserole crust with ketchup for pizza sauce.