Depending on what genres you read you can buy some of them from publishers. There are plenty of ebook stores where you can buy books. Some are DRM-free, others have the DRM.
I chose my Sony for several reasons, one was that I could borrow books from a library if I wanted to, but it wasn't the deciding factor. Mainly it was that I wasn't tied to Amazon. The wireless was good until I learned that Sony sold DRM'd books; but I can get most of the books from online, and DRM free.
Learning how to strip the DRM can also help to open up bookstores if you want to go that route.