I went to Best Buy today. I went to the only one in my area that SAID it had the Sony 950 in stock on their website. It didn't. It didn't even have a demo model out. I spent quite a bit of time there and I tried the Kindle 3, the Sony 350 (to try the interface, etc.) and the nook. I ended up walking out with the nook. I have until the end of January to return it with no restocking fees so I'll see how I like it. It was comfortable, I liked the ergonomics of it, and it felt right in my hand. The Kindle did NOT feel comfortable. The page forward button was at an awkward angle for how I was holding it. Now to be fair, it's possible that was due to the massive security device on the back. But I could tell it would cause thumb pain (which I am prone to). I know I initially said I wanted the ePub, but I figured I would try it out anyway since it was there. They were sold out but they did have the demo model out. The Sony touchscreen was nice, but I didn't like other things about it and I decided in the end I just couldn't justify spending THAT much money. The nook was more in a realistic price range for me. I got a nice cover, a light, and the nook for $30 for buying together.
I did not notice a huge difference in page turn times or ink darkness between the three, so I went purely on price and feel. If I don't like it in a few weeks I'll return it and try again.