Fiction: I dunno but maybe "Anathem" by Neal Stephenson.
I think Anathem is Stephenson's best. The Diamond Age is also really good. For every one of his books, I just wish he could write an ending that matches the quality of the rest.
Hard to choose for me, but I might cast a vote for the Baroque Cycle, although I love almost all of his science fiction as well.
Fiction: I dunno but maybe "Anathem" by Neal Stephenson.