Real books for the simple reason I don't have to rely on technology, at work I read all the time on my desktop pc(when technology goes down, no can work or read), which is ok, but for personal or academic development, printed books all the way(I'd go mad if my personal/academic books would disappear). Not many ebooks in academia for that matter, popular books, eh, prefer the printed book, with the exception of the newspaper, I like to read the enewspaper.
90% printed books/10% ebooks/enewspapers