I will have to give my voice to Dune by Frank Herbert. Given he is one of the fathers of Sci-fi. Plus the books is just a classic.

Isaac Asimov - Foundation Series



Unlike most Books, it doesn't focus on single individuals, it focuses on the founding and growth of a Galactic Empire, from it's very beginning as a single World on the Edge of the Galaxy to a Civilization that spawns across almost half the Galaxy. During the 500+ years History it goes through numerous changes in policy, politics and science. I read it about once a year.