I noticed that books I enjoyed the most always had a common theme: a group of friends, with a weirdly codependent dynamic, frequently having intellectual and/or philosophical discussions. Like "The secret history", for instance. Cortazar also had similar "clubs" in some of his books. I like dark and sick themes, preferably in not too modern setting (I get annoyed when there's too much internet and smartphones in books, we have enough of it in real life). Sorry if it's too weirdly specific.
by no_brain_no_cry