I have a Nook and I love it. I travel every week and no longer have to worry about something to read. When I finish something or don't feel like reading something I've already started, I have options without going into a bookstore at an airport.
I did a lot of research on e-readers and the two that I narrowed it down to were the Kindle and the Nook. I chose the Nook because it includes functionality that allows you to borrow e-books from your local library (the Kindle doesn't provide this option). It also has a replaceable battery (for that time in the future when it no longer will hold a charge) and it has unlimited storage because it has a micro-sd slot.
Hope that helps.