I have them in different formats, and every one serves a different purpose. I think I have an eBook, an audio, a signed copy, a hardback, a really battered on that was my first, one that I lend out to people, and one that I use for normal reading that's covered in sticky notes and highlighting and graffiti (Mainly Allomantic symbols, glyphs, and Aons ). I'm kind of OCD when it comes to books I only have 4 sets of Words of Radiance. It's kind of disappointing.