I had a Kindle ("had" because I had to sell it to pay bills), and I LOVED it! I want another one, some day when we can afford it. My husband had one too, and he also loved his. They have a HUGE selection of free books on Amazon.
You can get a Kindle on Craigslist for around $75 now. (Are you in the US?) Just make sure you get the 3G with WiFi, it makes transferring books from Amazon to your Kindle a cinch. My husband accidently bought the older one for himself, so he always had to hook it up to the computer, and the whole process was kind of a pain. With the newer one all you do is click "Transfer to my Kindle" on Amazon and voila, there it is.
Also, I loved the screen, you can still see everything crystal clear in full sun light. It's awesome. And the battery life is amazing too.

I don't know anything about the Nook, sorry, no help there.