I prefer to borrow any book that I expect to read only once (yes book publishers nightmare I am ). I would prefer to borrow ebooks, but that choice is most often governed by what format is available to me. That means I mainly borrow paper books at this time.

If it is a book that particularly appeals to me, and I think that I will want to read it more than once, then I will purchase it. The same preference considerations as for borrowing a book apply, except that any book with graphics I will always go for the paper book.