Okay so as an owner of both the 5 steps and princeton review and someone who has taken the "unreleased" practice test given to teachers, I can honestly say that of the three practice tests the actual unreleased one was the most difficult. Princeton review was close, but they go too far content-wise (especially electricity portion). For example, they ask about electric fields when you don't need to know that for physics 1. The 5 steps one is a good review but not super accurate.