It actually depends on the school and person, each school has a different teaching regimen and each state DEFINITELY has different teaching regimen, it also depends on the person.
From least to greatest here it goes.
AP US: For me I swear this is the third AP class ever after psych and government for me, basically as long as you read and have your noyes you'll be fine. Just remember, definition does change depending on the time frame. For example impressment today is not the same as impressment back in the 1800s, so when using your notes be sure the definition matches with what was back then.
AP physics: Physics as a whole is fun, you'll enjoy this class, this is a bit more demanding than history but you'll be subjugated to taking multiple quizzes but the quizzes are easy, everything should come from the book, it's also good to do dome extra research to broaden your prospective of topics ESPECIALLY for this class, or it will suck...horribly.
AP Lang: My teacher at least made this the mist rigorous course in the school rivaled only by the IB World teacher, the work load is immense but the work itself is easy, if you don't like reading you better begin, also try to read some poetry and analysis here and there but that's more literature. Tedtalks are a big one, and mind maps, try to master the dreaded mind maps ASAP if you can. But AP Lang does help you to write better and to analyze what you're reading and not just reading for the sake of reading. It's a good lass imo, but lit is slightly easier but you'll have to wait until senior year for it.
AP Foreign Language: This class is worst than the Zombie apocalypse, I've heard some people try to take it just because they speak the language, but I speak English but that doesn't make AP Literature easy. Know the respective language well enough that you can hold long conversations in then, because AP French for me was at best hard but I still passed, without that the respective AP foreign class will be hell