Kindle is an e-ink, there is no color screen, nook has a color screen but isn't e-ink (it's like reading a computer screen).
The e-ink can be read outside in the sun, it's just like reading a book page. A nook can't, it's like your phone screen, ipad screen, laptop screen.
For me, I don't need color in my ereader so Kindle was the only way to go. I also got a kindle hard cover with built in light so I can read it in the dark. If I fall asleep the kindle turns itself off after 10 mins of not changing the page. Since the kindle is plugged into the cover the light runs off the kindle charge so the light turns off too.
Ask your dh what he wants. To me a nook makes no sense because I can't read it at the beach, for others they want to read magazines so the Kindle makes no sense.
I LOVE my Kindle!