I can't bring myself to get an e-reader, as I see them driving bookstores out of business. I LOVE BOOKSTORES!
Paperback if I'm carrying it or need a book I can toss in a purse. I do have a Hardback Silmarillion in my car. The paperback version didn't hold up well enough, Don't dare do audio books when I'm driving. I get too into the story. How to explain to the cop that I thought I was riding an eagle to the Carrock.