This question always comes up. It truly depends on your learning style AND the geographical area. If you need more lecture - then Princeton. If you are more independent - then Kaplan. In my area, Princeton always seems to have better scores - but that is different around the country. The best advice is to ask those who have taken the class from your institution.
That really depends on the area that you live in. In some areas, one is better then the other (In Miami-Dade county, Princeton Review is much better then Kaplan). In any case, they both have good materials. I suggest you ask around your school or people that have taken the course to give you a clearer answer.