I'm sitting here, looking at my bookshelf, and can see how my book format taste has evolved.
Many, many moons ago, I used to buy hardbacks. As soon as a book was available, I would buy and read it. Then I realized had a back-log of unread hardbacks! The next thing I knew the paperbacks were out and I still had not read the hardback version, so I switched to paperbacks. Hey, since I was behind on my reading, I might as well wait for the paperback version; plus, it was cheaper.
So for all the paperbacks, I need more bookcases, hey no problem, my office can "squeeze" in one more bookcase. Now they are all packed!
Last summer, I finally broke down and bought a Sony ereader... and I love it!
I no longer have the room to store the paperbacks! So basically, I prefer ebooks, though I still love my paperbacks. But it's great to be able to carry several hundred books on your person!