It's definitely the hardest in my opinion since it requires a knowledge of art and then it has the time frame of World History with the depth of Euro/US. And then once you get to the 1900s, you make new friends: the isms. All of them.

AP Physics C has around a 31%-rate of getting a 5 with a mean of 3.55. APAH has around 12%, has around double the test takers, and has a mean score of 2.85. Statiscally, APAH is harder.