I was wondering if these e-readers allow you to read the books you have without having to be "online"? Also, is there one particular e-reader that is better than the rest. Thanks all!
Yes most (if not all) of them work offline because you download the book to the device. However this will not be the case if you use a Cloud type reader.
As thescottz says - you download the digital copy of the book to your device - at least you do in all the eReaders I have used, so using offline is the norm