Much like Hawki I'd have to say Brave New World. But I am a big fan of the classic sci-fi era guys like Clarke and Matheson. I'd point to something like Clarke's collaboration with Steven Baxter for "The Light of Other Days" as something really special.
And off beat choice for fiction and non-fiction... "Dirty Jokes and Beer: Stories of the Unrefined" by Drew Carey is surprisingly good. The first half is nonfiction, his life, his career, the tv series, and being a comedian. And it is fine. Good if you are a Drew Carey fan. But Drew described it in the book as "the part he wrote with a gun to his head." What he wanted to write was the second part of the book, a collection of short stories. These short stories are really outstanding. The audiobook version read by Carey himself is pretty good as well, but a warning to any who go that route. The audiobook does not contain ALL of the short stories, but does include a sequel to one of the stories that is NOT in the audiobook version. Better to read the book, or at least that story before going audiobook.
But if I'm honest I have a amalgamated hardback (gilded edge too) copy of the entire Hitchhikers Guide series that is actually my favorite thing to read in the world.