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.
Short Stories Anthology of Hemingway. Had it so long I come back to random stories. And this book from Time Magazine I ordered 85 years of Great Writing. Random articles selected and sorted by topic, business, social life, art, medical ne, National Experience, etc. That deal with History. I can read random articles. Amazing book