I have a Kindle 2. And I love it. It’s really great for reading fiction – not so much for non-fiction where you might want to make notes, highlight, only read one chapter. But for fiction, awesome. It’s really light, and it’s easy to read with one hand. The controls on the newer Kindles have changed a bit, and I don’t know how they are for reading with one hand. But, the cheapest Kindle is now $79, the cheapest touch (and just fyi, touch makes it harder to read with one hand, because you need one hand to swipe and one to hold the thing up) is $99, the color tablet version is $200, and the most expensive version is $260.
I don’t really know the Nook very well. I’ve held it in the store a couple times, seemed pretty much the same as the Kindle (but again, the controls have changed since I was in the market, so could be much different by now). The cheapest Nook is $99, the most expensive $250.
I think (but could be wrong) that one big advantage of the Kindle is that some authors just publish their own books on Amazon via ebook, but I don’t know if Barnes & Noble has the same kind of market for self-publishing. And then the books are in Amazon format, which you can convert to Nook format, but it takes a bit of doing and some of the formatting might get lost.
ETA: possibly a good and current review site.