"Best" is a very strong word. It implies the application of objective criteria in such a way as to obtain a neat distribution of value. One candidate is better than another, which is better than another, etc. on some cosmic ladder of excellence. "Best" strikes me as way too much of a slog.
I read a fair number of books in 2013. But I won't tangle with "best." Instead I'll go for "sticky." Here are five books which, after two months of sleep deprivation, I still manage to recall having read.
1) Far from the Tree, Andrew Solomon. The longest book I've read since an ill-advised slog through Don Quixote, but about thirteen thousand times more interesting. Solomon's doorstopper is a meticulous charting of families rived -and bound- by difference. How does a parent cope with a child who is not merely different from himself, but categorically distinct: deaf, or autistic, or a prodigy? Pretty much the best book since sliced bread, if sliced bread were a book. (But don't eat this book: Paper is not tasty.)
2) The Interestings, Meg Wolitzer. I am a huge sucker for books in which protagonists reexamine their youthful choices, and I am a sucker, too, for Wolitzer's sedimentary writing: the slow layering of detail into a luminous whole. In recounting the journey of a close knit group of friends from teendom through middle age, Wolitzer explores what it means to be talented -and, in particular, marginally talented. Since scads of us marginally talented, this makes for some satisfying literary navel gazing.
3) Bring up the Bodies, Hilary Mantel. The face-smashed-into-the-plate-glass, bloody-nosed immediacy of this novelization of the fall of Anne Boleyn is wild and bruising and very, very lovely.
4) Going Clear: Scientology, Hollywood, and the Prison of Belief, Lawrence Wright. I mean, WOAH. Read this before the Scientologists enturbulate the world.
5) Operating Instructions: A Journal of My Son's First Year, Anne Lamott. Lamott's hilarious recounting of birthing and raising a colicky boy child by herself at 35. A nice dose of hey-it-could-be-worse for your average new parent, and plus Lamott lived to publish this book, so that's vaguely reassuring. Maybe I'll see you in 2014 after all.