Both. Fiction is what made me fall in love with reading and I still continue to read fiction the majority of the time, but I do read non-fiction once in a while depending on if the topic interests me. I read Marilyn Monroe's biography and it made me not idolize her anymore. Her life was actually depressing as fuck. I read a lot about nutritional science for some reason, books like The China Study, The Great Starvation Experiment, 80/10/10, The Starch Solution, and things like that. I do love non-fiction because I love learning, but I read as a means of escape I guess. Not that my life is boring or anything lol I just think living in a world with hobbits, vampires, werewolves, elves, dragons, and magic would be a lot more interesting.
I have a policy where I avoid fake stuff - this means no movies unless the movies are based on true stories, inspired by true events, about true events, or teach an inspirational moral message so I chose science and popular subjects. Before I started saving up for school I used to go to the bookstore everyday to read books in the psychology, religion and mental health section. I also enjoy traveling books and art history books but fiction bores me.
I like fiction but historic and scientific books hold my interest for longer because I know it's real and it actually happened so finding things out is more shocking, plus you learn new things. I don't read often though.. only write.
I use to loved fiction. But nowadays I find myself reading all non fiction. I'm in love with surgery so I read books based on surgeons or med students experiences and biographies. Does that count as science? :P