Not including short story collections, poetry collections, anthologies, etc.
For me, I believe it’s Oroonoko by Aphra Behn because it was on the syllabus for three different classes that I took in college. Other than that, the most I’ve read a single book is twice, and that was Telegraph Avenue by Michael Chabon. I’ve read Dracula 1.5 times. Didn’t finish it the second time around.
The Road Home by Ellen Emerson White.
Randomly picked it up from the library in middle school and must have read it like 8 times. Still own a hard copy of it in my personal library.
It’s an exploration of self doubt, healing and recovery. A journey through the personal growth and development of someone who decided to join the military because they wanted to become part of something, to be important, and it fractured everything they thought they knew about themselves.
It had a huge impact on my younger self.