I have never used PR
for Calc, but I did use Barron's. Barron's explains things well, gives you lots of practice problems (like 100 in each of 15 chapters or something) and explains answers, and has practice tests that are harder than the actual AP test. When you get to the AP exam, it's easy. I would recommend Barron's. I haven't gotten my AP score back yet of course, but I'm sure I got a 4 or 5, for sure.