I usually read Fantasy, sci-fi, some romance, and other non-fiction.
How about some Isaac Asimov and his series Foundation? That stuff is complex though 
This topic is turning into a book club discussion(!)
Asimov is pretty awesome, especially foundation, most famous are his robot books and his three laws of robotics
I enjoyed all of the books i read from him.
Frank herbert's dune is quite similar(inspired by foundation) and also very immersive.
HG wells is my favorite scifi writer, his stories are usually quite short and predictable in a certain way that i enjoy but very visionary.
He wrote allot including some very different works in his later years, which are much longer and less fiction like, written like history books, or a weird plea for a world government. Really weird but intresting.
If where going into this direction then i'd also advise reading up on fahrentheit 451 by Ray bradbury and brave new world by Aldous Huxley, if you like orwell's 1984'ish scifi.
