Logos

I was re-arranging some furniture recently, and decided to move a bookshelf into another room. I noticed I had read almost all the books on the shelf, and found it strange that I didn't have many waiting in the wings. I know I had a bunch in my to-read pile, but where was the pile? 

Seems I have been reading ebooks either from that huge online bookstore or from the library, and have a virtual stack a mile high.  

Then I began to notice the books I did buy. If I want to read a book, I get the ebook. If I want to read a story, I buy the book.  I then couldn't decide whether to display them by color, or by publisher's logo... 

Do you prefer books or ebooks? What does it depend on?