The Bible is my top non-fiction read since I prefer to read it yearly. [There's bound to be difference of opinion on it's non-fiction/fiction status.] Other devotional reading brings a close second.
Politics is next on my reading list since I am SO wet behind the ears politically: at least being able to communicate intelligently about it. Technical reading used to come in a close third since I maintained several web pages but I threw it all out (only the web pages-not the books!!!!!) for lack of interest in maintaining it.
Biography, memoirs, history fill out the rest.
WHEN I read fiction it is usually about books, libraries, some si-fi, fantasy but time is precious so I tend not to spend too much time in this camp: escape, yes, that would be why I go there....