Which book did I have to read, did not want to read, but ended up liking?
Bartleby the Scrivener, by Call me Ishmael, erm, Herman Melville. Moby Dick was probably the first school-assigned reading I DNFd. I took the lower grade rather than finish that book. So, when ol' Bartleby showed up on a syllabus there was a lot of gnashing of the teeth. I prepared my tirade on the many flaws of Herman Melville and his writing (having only partially read of Captain's Ahab's hubris), but when I saw it was a short story I simmered down and opened the anthology of western dead white guys' vaunted short works.
Friends, I loved that story. Bartleby broke my heart and the narrator made me so damn angry I fumed for days. Any story that can evoke a lasting emotional reaction, well, I had to revise my opinion on Melville.