I would highly suggest buying and trying them both, then return the one you don't want
I've never looked at the Nook closely. For me it's a contest between Sony and Kindle. I LOVE Sony's Collection feature (the one on the Kindle is terrible), but I really prefer the weight/balance and size of the Kindle. I find it easier and more comfortable to hold, especially because the keyboard provides a good place for me to put my thumb.
But that's a personal preference that you can't gauge just reading through stats. You say the Nook is heavier, but despite that, you may find it more comfortable to hold.