I bought the Cybook and I had the same problem as you. The deciding factors for me was support for more formats, a good attitude from Bookeen about supporting many formats, dictionary lookup support, less weight and thinner form.
At first I though the images of the leather case gave a bad impression. Then I read it had magnets inside to keep it closed. And I realized that it did not look like an expensive electronic object inside the case and that is an advantage.