The fiction books I like the most are imaginative fiction such as science fiction and fantasy. Of those books, the ones that I like the most are the ones which try to create a setting that is takes into account our knowledge of natural science, history, and anthropology to create worlds and characters that are believable and could almost be real worlds. I am also interested in historical fictions for this reason.
Some examples of the books that I consider realistic either in terms of human nature or science includes those of the series, Malazan, Book of the Fallen, by Steve Erickson who draws from his background as an archaeologist to create a world with a detail-rich and wonderfully grim setting. Earthsea by Ursula K. Le Guin who does a good job at depicting cultures that are non-Western in a high fantasy setting, is another example. Lord of the Rings is another example where J.R.R. Tolkien uses his expertise in ancient languages to bring to life his fantasy world with his constructed languages.