Such a simple question, but so hard to answer. My favorite genre depends on the mood I am currently in, so one could say I can really enjoy any type, really.
However, I really, really like the books that are deep, leave you questioning and have a (good) mind twist at the end. They can be of any type of genre, but they are mostly dramas and thrillers.
EDIT: That is going to teach me to read the subforum name as well as the post itself.
Answer remains the same really.