If you are wed to B&N, the problem is going to be that Amazon is a locked down ecosystem. There ARE workarounds, but it requires effort on your part and third party software and is a constant cat and mouse affair. However, there really is no denying that Amazon is the 800 lb gorilla in this space. They have just about everything, their hardware is some of the best out of the box available and their constant sales are unbeatable IMO.
Well, I guess the main problem is that these different companies are designed to not work with each other very well. Yay capitalism I guess. If you don't want to mess with cracking DRM, I guess the question for you is, which ecosystem are you more invested in and do you wish to put more into in the future?