I'm not at all particular about the cover in paperback books, but if I'm buying a hardback book and spending more money, I will always choose either the first edition (if it's within my budget) or the one with the prettiest cover. The story or information inside a book is always the most important thing, but if I'm spending my money on a hardback book to keep, I also like it to have aesthetic value. (I've never read the book Babel, so these are just general thoughts.)