Malak wrote:William Goldman in general (care to choose?)
First of all, none of Goldman's books are "screenwriting books" per se, they're either personal memoirs or collected essays about film. But along the way in all of them he talks a great deal about his theories of screenwriting.
Adventures in the Screen Trade was his first, most infamous memoir, about his career up to the point when he wrote the book in 1983. So it discusses the making of Butch Cassidy and other early works of his, but not Princess Bride which hadn't been made yet. The book was infamous because Goldman told tales of his experiences and actually named names - if he thought someone was a d-bag, he said so.
Which Lie Did I Tell? is the followup that covers his career since writing the first book - the chapters about Princess Bride, Ghost and the Darkness, and Year of the Comet are especially memorable.
The Big Picture, on the other hand, is mostly a collection of magazine articles, including many of his annual Premiere magazine reviews of the Best Picture nominees. In which he explains why - in his opinion - Titanic was a great movie, Private Ryan was a badly flawed movie, Shakespeare in Love and Life is Beautiful weren't very good at all, and so on. Also some interesting insights into why Jim Carrey is important to movie history, and other fun topics.
They're all great books, but if you want to get the flavor of Goldman, then maybe Big Picture, being a smaller book with bite-sized chapters, might be the place to start.