I think you have to know what you want to use it for. Just reading? Then decide if you need the library feature right now - the Nook is for you. If you don't care about that and like Amazon better than B&N and can wait for the library feature, then the Kindle would be it.
If you want something you can do more with than read books, then get the Nook Color. Or if you want something backlit, then the NC is your only choice. I got the NC because I wanted something backlit and hooked to libraries right away. I have yet to buy a book (B&N has tons of free ones), and can't keep up with what I need to read. I *have* purchased a few apps for the kids like Angry Birds, and I'm enjoying some crosswords and playing freecell solitaire, too.
Everyone loves what they have so as long as you figure out how you want to use it, you really can't go wrong with any of them!
I really haven't seen anyone post that they regret what they bought.
