Anything and everything.
When I'm at home cooking and have to wait for something to heat up I read whatever is within reach. A newspaper, flyers, take out menus; even the food packages.
When I'm out I absorb billboards, advertisements in windows and on cars, road signs, license plates, receipts of things purchased, etc.
When it comes to books I'm a little more picky. Maybe even a bit snobby. Fiction has my preference; I've never really been able to get into the non-fiction stuff, except for philosophy. Within fiction I try to stick with what would be called literature with capital L. That's just because I don't like to read books just for the sake of being entertained. There always has to be something more to get out of it, whether intellectually or emotionally (and ideally a combination of both).
Favorite genres are children's literature, modernism, modern American literature, postmodern fiction and short stories. Newest addition is East Asian fiction, also the first time I really find joy in reading poetry.