Apart from books on the art and craft of writing, I primarily read YA. Since I write YA contemporary and YA sci-fi dystopian (so far), I read books in both categories.
On the art and craft of writing, I have read: On Writing, Bird by Bird, From First Draft to Finished Novel, Formatting & Submitting Your Manuscript, Writing Great Books for Young Adults, The First Five Pages: A Writer's Guide to Staying Out of the Rejection Pile, and Outlining Your Novel: Mapping Your Way to Success, among others.
In the YA category, I began with: Speak, The Chocolate War, The Hunger Games, 13 Reasons Why, The Mockingbirds/The Rivals, Divergent, Delirium, Ashes, Summer on Fire, Boy Toy, The Astonishing Adventures of Fanboy and Goth Girl/Goth Girl Rising, Hero Type, Destined, Hunted, Scars, Crank, Uglies Quartet, Daughter of Smoke and Bone, Shatter Me, Shine, and The Beginning of After, among others.