Kindle or Nook?

It goes without saying that I'm a big supporter of libraries.  Sharing books is good for the environment. 

But if you must read new releases, the Nook or Kindle pay for themselves if you choose to buy around 16 new releases via e-book rather than hard copy.  Plus, e-readers save trees, so I consider them to be green technology.

I've weighed the differences and I think I've decided - but I'd love to know what you think.  Please take my poll!