I really like the paperback version, because of the outlined people, and the circus in the background kind of feel, but it just seems a bit too busy, and overwhelming compared to the hardcover version. The shrub made out of clockwork, and the bird flying from the girl's dress are nice touches, but it just all too much.
I love the hardcover one. The title with all the swirly cues, and the circus being the main focus, while being held up by an extremely large hand, that's just awesome. I also really like the swirly tree there, on the arm, and night sky.
So, the Hardcover is my winner.