Both are good products and are going to provide about the same protection to road debris.
[b]Finish[b]
Cox - anodized several colors
RadGuard - powder coated clear or black
Weight
Cox - lighter
RadGuard - heavier
Installation
RadGuard - bolted brackets top and bottom
Cox - zip ties top, bolted bracket bottom
I suppose given the choice I'd rather bolt something on than zip tie it. But the reality is zip ties are completely adequate for the purpose at hand, bolting might be over engineering. But if there's any real penalty of having the upper mounting brackets they'd only add an ounce or two of weight.
Hub recently demonstrated the futility of over engineering a solution for affixing components. Using specialty glue is completely adequate and the superior method compared to drilling holes through frame rails and using nuts and bolts. The holes compromise the integrity of the frame rails (in that specific case anyway) and nuts and bolts add unnecessary weight. Sure it can be bolted on, but it's not at all necessary. I wouldn't zip tie or glue the engine into the bike. But for a radiator guard or electrical component zip ties or glue are perfectly suitable.
Ridiculous claims - the type of thing that's nearly offensive
RadGuard - "This frame will protect your radiator core from crushing on side impacts. This can happen just by the bike falling off its stand."
Can is the keyword here. It can help you live longer too, that doesn't necessarily mean it will. It can help reduce global warming. That it can do something doesn't mean it does in any meaningful way.
RadGuard offers no "radiator protection guarantee", which proves this is just marketing bullshit. You can sleep better at night believing this thing will protect your radiator in some meaningful way if your bike falls over or you have an accident. Just think, when that grey hair T-bones you at 50 mph your radiator will be just fine - all thanks to RadGuard. 
My old bike fell over 3 times, even once a low speed low side (let a friend ride it). Guess how many times the radiator busted open? 5? nope. 3? nope. 1? nope. 0. If you said zero you got the right answer! I knew a lot of people their bikes fell over time to time. Never heard of radiator being damaged purely from the fall, not even a couple friends that raced and had accidents busted their radiators! RadGuard clearly wins this category.
Hell how many people have had their 14's fall over in the last 6 months here? At least 5. I don't believe any busted their radiator and none can credit their RadGuard.
