AFAIK the higher the caranuba, the better it looks (which is always debatable) and the better protection it provides for the short period of time it lasts (the synthetics generally last longer but the argument is that it doens't look as good) honestly I dunno about the p21s stuff...and it's more of what i think i know--not definitive--(sorry but on the chance that i'm right hope it helps)
The 100% is better, BUT I wouldn't limit yourself to just those two choices. IMHO Auto Glym HD Wax is better than both of those, and you can pick it up locally at Wally World. I also like Sonax Premium Class, and Dodo Juice Hard Candy a ton more than any P21S product.