We just recently bought 2 Sony Readers (PRS600)...one for myself and one for my husband. I considered the Kindle, but rejected it because there's no way to check it out ahead of time unless you know someone who has one and can try it out, which we don't. With the Sony, you can hold it in your hand and try it out. The Nook would have the same advantage over the Kindle, IMO; i.e., you'll be able to see it in person and try it out before purchase.
You cannot download books over the Internet directly to the Sony like you can the Kindle, but having had a Sprint air card in the past, that wasn't a big selling point for me since Sprint had poor service in the areas we travel. It doesn't take all that long to download a book to my computer, hook up the Sony, and transfer the book to it. Now, if the Kindle used the Verizon network, I may have been more inclined to buy it instead of the Sony, even though I wouldn't have been able to see it in person beforehand.