I bought the Nook with WiFi and 3G a couple of years ago and my husband gave me a NookColor for Christmas. I love them both. I have loaned my first Nook to my sister and kept it on my acct so she could read the books I have bought so far.
I spent a lot of time online researching before I decided on the Nook over the Kindle. The Nook has a "lend me" feature where books can be loaned to friends and family who also have a Nook (specific rules apply) and Kindle doesn't allow loaning. Our library (and most others) is starting an ebook loaning program which won't work on Kindle but will on Nook and several others. It has something to do with propietary issues with Kindle or Amazon. I love the backlit screen of my NookColor as I do most of my reading at night in bed. The NookColor has regular updates to the software and seems to get more and more like a little computer with each upgrade. I love the touch-screen dictionary and the ability to bookmark pages or passages. You can also sent passages to friends via facebook and such.
But my MAIN reason for choosing the Nook is because I can go down to any Barnes and Noble if I have questions or issues and talk to a human face-to-face. That is really important to me (although I haven't had issues to date). The B&N closest to me hase a weekly tutorial/forum group meeting for Nook users.
Anyway--I have never regretted my choice. Good luck making yours!