You know, the classes where you read classics and analyze them for themes, symbolisms, etc.
They taught me to read closely and pay attention to and find the meaning in details. They also fostered an interest in human psychology and gave far more interesting and rich examples of characters to consider than just reading psychology textbooks. Finally, they taught me about tone, style, and voice, and how to manipulate those in my own writing. I also always preferred history courses when a novel or memoir was included, as it made the usually dry history come to life for me.
The reading portion of the ACT has some of this kind of analysis.
As I advanced in my high school career, I found it harder and harder to find time to read. AP Lit encouraged me (more like forced me haha) to return to my habit and expanded my palette to include more classics. I could see myself now reading more than just YA books and like Harry Potter in college. I love the analysis part and discussing these books with others.