I'm glad everyone else is also not picking just 1 book :p The Hitchhiker's Guide series is undeniably first for me. Aside from the hilarity and great writing i

I'm glad everyone else is also not picking just 1 book :p The Hitchhiker's Guide series is undeniably first for me. Aside from the hilarity and great writing it's also very nostalgic for me. One Christmas my dad gave me the Hitchhiker's collection, Going Postal, and Catch 22, all great books. Permutation City by Greg Egan. Found out about it from an HN comment. If you're interested in scifi about AI and brain simulation, this is it. Also looking at my bookshelf I've got to throw in Multiversity by Grant Morrison (and 8 great artists). It's a graphic novel but it's just so darn good. If you're not a comic-book superhero fan, it might not be too great. If you are, it's a great meta story and really rewards analyzing it for symbolism. Grant Morrison really knows how to treat comics as their own unique medium. Each chapter is supposed to be the #1 issue to a new comic series (in different canon universes drawn by different artists), except a DC multi-verse event tangles all their stories together.