I know the Kindle will last, if you make sure the wireless feature is turned off....
When my sister gave me the Kindle last year, the first thing she told me was to shut off the Wifi. The Nook is in color and is backlit, and even if I keep the screen dim, the battery needs to be charged almost every day. The Kindle? Maybe once every six weeks. She was thoughtful enough to add a little detachable light for it, which is good. Living in Alaska, one experiences frequent power outages.
I love the Kindle!