Carol brings up a very good point. If like me, you prefer to see the EBR in action in order to get a better idea of how the device works and yet you don't know enough about them to do a proper hands on evaluation, go to YouTube and search for videos of Kindle vs Nook or some variation of the search.
There you can virtually experience the various EBRs and you may see things about the operation that you like and things that you don't like. It certainly helped me make my decision. I wanted to like the Nook (no knocks on it either as I think it is a fine device). But for me I just knew that the virtual KB and virtual directional pad would frustrate me, much as my touch screen phones have done. Not that they don't work well most of the time... it's just those times that they don't are enough to turn me off.
With the least expensive versions of each being only about $10 apart, price is not a deciding factor. With the vast library of books available for each, that is not a factor. If you do want to borrow books from the library and don't want to follow the path of file manipulation, then the Nook (or other epub EBR) may be better for you.
Edit: have you reviewed the EBRs in the
comparison matrix?