What would you use it for?
What formats of ebooks do you want to use/support?
Will you be getting content from strictly one provider or many?
What would be your primary purpose for this device?
How close are you to a Barnes and Noble? and/or Are you comfortable working "solo" via
Amazon?
I had the same delimma this Christmas. My first gen Nook was breaking down and I wanted a new ereader. My son (17) was also reading all types of material -mostly classics- off his tiny phone screen.
My son likes to root or mod things. He's done it with PC's, Xboxes and other systems. I knew that he could root the Nook Color and use it as a mini android tablet and not utilize the data on his phone as much. And as I suspected, he did that on 12/26. He now has a mini android tablet that he can use to check his email, play games, use apps and still read. Even if he didn't mod it, he would still use it as an ereader. He gets files from various formats (epub, pdf) so he could use them via the Nook.
However with my Nook, I hardly ever used the sideload option (epub/pdf) and the one hour read in store free option. (In fact, I ran into problems trying to use the read in store feature back in November).
I decided to go with the Kindle Fire. I didn't need the free read in store, the ability for epub or pdf files and could work solo via Amazon. I wanted a substantial item that could do more than just read books. To me it isn't an Ipad Lite, but it is an ereader first to me.
I looked at all the free book options available for both Nook and Amazon. Over a one week period, there seemed to be more options available for Kindles than for Nooks. Now I rely on free material versus paid material so it was important to have a large selection.
I do like that I have utilize the andriod marketplace on the Kindle. I also like that I can rent a book per month (i already did it and finished it). I like that I do have specific Prime benefits- although I'm not sure If I am going to extend it.