I tried something called Coolreader and thought it was a very nice reading app. It isn't as customizable as Moon+, but not too far off. The main issue is that it has no library feature from what I see. What about the Nook Android app itself, compared to the stock NC application?
I'm going to test all of these applications again and try to stick with each a little longer, but so far for overall use I really like the stock reading application. In many ways it is simplistic and lacks features, but at the same time it seems to have a good presentation. If only I can grab features from each of these and build the perfect reading app.