This would require choosing a favorite book. I can't even begin to do that.
I have books that I've read so often that I know their terrain like a favorite hiking path: A Prayer for Owen Meany, A Walk in the Woods, Bet Me, Outlander, A Tree Grows in Brooklyn, Confederates in the Attic.
I have books that are so gaspingly wonderful and provoking that I've only read them once or twice, but I will do it again- when I can breathe again from the first time: God's Hotel, The Secret Chord, The Hour I First Believed, Smoke Gets in Your Eyes, Dear Leader, Religion for Atheists.
There are books that I've read repeatedly because of my occupation and their call to me: Jonah, Mark, Ruth, Judges, Revelation, Romans.
There are the books that I won't read again, but I recommend so highly: Five Days at Memorial, An Unquenchable Thirst, It Gets Better, Full Body Burden, The Secret Life of Henrietta Lacks.
So I've completed flubbed the prompt.
I will give you this opening line:
"The evening is typical enough until the dog begins to choke."
It's the first line of Those Who Save Us by Jenna Blum. This book was such an unexpected plot that even though I've read it 3 times, my heart beats faster just looking at the cover.