I travel a lot and don't always have access to wifi or cell signal. All things being equal now (Nook HD rooted) which is the better device/hardware/screen device?
Go for the Nexus 7, best one there is.
I've got mine for about 5 days and I love it.
Nook does have higher resolution, expandable MicroSD slot and HDMI. But consider if you are really going to use that. If not, go for the Nexus 7. You won't regret it.