Quotable novels are all alike; every unquotable novel is unquotable in its own way.
I imagine other than first lines, most novels are fundamentally unquotable from memory. This isn’t Fahrenheit 451 where we all get to memorize a great novel for posterity. I have spent forty or fifty years underlining important or moving passages in novels and later quoting them in theme papers and essays, but I’ll be damned if I actually memorized them. If I had to choose, though, I would say I can recite Finnegans Wake more than any other novel, and that includes Ulysses, Anna Karenina, and Catch-22. However, The Maltese Falcon is actually the book I can recite the most but I don’t feel it’s fair to use it since I probably memorized most of the lines from the film (the book and the film are almost identical).
The real problem with this question is that vague word “book” which I have interpreted as “novel.” Here we should allow it to refer to plays and poems.
In Graduate School I did an intensive study on Macbeth. It wasn’t long before I realized I could recite the entire play, almost without error. I remember going to parties and after the dog finished doing tricks, I would dramatize Macbeth playing all the parts (I was an especially good three weird sisters) just as long as the beers kept coming. Smaller parts from other Shakespeare plays were also commonly embedded in my memory (loved Richard III) as were several other playwrights. Since my concentration in Grad School was William Wycherley, I could recite a pretty good Gentleman Dancing Master. But the real field for memorization and recitation was poetry and I had plenty of poetry from Chaucer to Roethke. I did my senior project as an undergraduate on Ted Roethke and you don’t have to read and study a poem too long before it curls up in your memory. I found this technique of literally memorizing the poems invaluable when studying a poet and especially when taking one of the few examinations they forced on us (we mostly wrote papers).
From High School and most of the way through College and Grad School, I was unabashedly under the spell of John Keats. Whether through study or just repetition I could recite many poems by Keats and could even stumble through some of the longer works. Even today when I pull down a volume of Keats’ poetry I am blown away by the poems: rhymes are easy and evocative, poems are lush and memorable. It isn’t clear to me why I dropped a focus on the Romantic poets but one suggestion by my advisor might have had something to do with it. He asked me one question and suggested it for the thesis of my advanced degree: Why is it that the Romantic poets—Wordsworth, Coleridge, Keats, Shelley, Byron, Blake—could not write a decent play? I might have thought about this one and realized I would have to read and study some really awful plays and soon after change my concentration to Restoration Drama.