Both. I have a large personal library and countless PDFs (books, reports, articles, etc). And I routinely research online. The method doesn't matter. The information and credibility does.
Agreed. I'm also big on both. As much as I like being able to access some things quickly online, in an e-book, etc., sometimes I just want to be away from a screen, and paging through a good book to see if there's something new to learn, refresh myself on, etc.