Depends on one's priorities. As noted, I'm unclear on restrictions on apps that can be stored on the Nook Tablet's SD card storage. In any event, my reading of various reviews doesn't suggest a significant overall advantage of the Nook. But, as always, YMMV.
I've seen 5-6 reviews comparing the Nook Tablet to the Amazon Fire and, as you've indicated, they each only give a "slight" edge/advantage to the Nook Tablet. The Cnet review does a decent job of explaining why you'd pick one over the other given the Nook's edge is so slight.