The difficulty of the classes really depends on the school. I’ll give you my opinion based on what these AP classes are like at my high school.
AP Calculus BC: Hard. Have you taken AP Calculus AB yet? While this class is difficult, it isn’t impossible. You have to be really great at math and knowing at least some calculus. If you get lost on something, make sure you address it. You don’t want to get too behind in the work. There were only 4 (maybe 5) people who took AP Calculus AB as juniors, and they were really smart (they were all in Academic Challenge). They didn’t find it too difficult, and all are taking AP Calculus BC as seniors. If you really like calculus, and took AP Calculus AB (and did well in it), then I say go for it.
AP Chem: Moderate/Hard. Some people love it, while other people hate it. If you love chemistry, then I don’t think you’ll have a problem at all. There were a few people who took AP Chem as a junior in my school, and they enjoyed it. There is a lot of reading and labs! It’s definitely beneficial depending on your intended major, and it will help you look competitive.
AP Computer Science: Very hard. My school started offering this AP class as an extracurricular (meaning that the class would meet after school). Not a lot of people joined. Everyone who took it complained that it was near impossible, and some even wanted to (and eventually did) quit. Two of the smartest people in my grade (in the top 10 of my class) took this, and ended up quitting. Don’t let this freak you out though, because it may be different at your school!!
AP English Language: Moderate. I took this last year (as a junior). It’s not difficult per se, but it is a lot of work. There is a lot of reading, writing, and analyzing pieces of writing. In this class, we wrote a lot of dialectical journals, essays, read a lot, had a lot of socratic seminars, and practiced MC and essay writing for the AP exam. Basically, that is what the entire class consisted of, in my experience.
AP Physics 1: Difficult. You really need to have an interest in physics in order to really enjoy and excel in this class. At my high school, juniors took Honors Physics, and those who were really interested in the subject took AP Physics. I think the level of difficulty really depends on what you think of Physics as a whole. Overall though, it isn’t the most difficult AP class. Have you taken a regular physics class at all previously? If so, that will really help, as you will sort of know what to expect.
AP US History: Moderate. I took this last year as well (as a junior). This AP class had the biggest turnout (there were like 90+ juniors who took it). It is a lot of work. Basically, the time in class would be spent writing notes. My teacher would talk about whatever we were learning about, and he’d have us copy down notes from Power Points. Because of this, all of the time outside of class would involve homework. Typically, out homework consisted of IDs (identifications), chapter readings (from the American Pageant textbook), MC questions from the textbook, and a couple of reading response packets with questions. Occasionally, we had charts to fill out as well. A lot of practice for DBQs and long essay questions. All of our homework was given in advance (it would be a lot of work at once), and we would have 1-1.5 weeks to finish all of it. We typically had 2.5-4 weeks to write DBQs and long essays. Best tip: do not procrastinate at all!! Time management is VERY important and essential for a good grade.
This is all just my opinion. However, it truly varies from school to school. I hope this helps!!! Good luck!