I have to agree with you. I like the American cover better because it's much more colorful and eye catching. The book is great too, if you haven't read it.
I like the American cover more in this case.Is creepy and slightly icky, and I look at it, and instantly think: zombie. For some reason, the AU one doesn't do that for me... despite the bloodred and the word 'ZOMBIES' on the cover.