I have no idea. If you want to know what types of essays usually win, look up the essays of previous years' winner and read them. If I had to guess, though, I'd say they are looking for essays that are very well-written stylistically and that show depth and thoughtfulness in the treatment of the subject matter. Anyone can throw together a bunch of facts about New Zealand picked up from the Internet. What you need to do is to find a way to personalize this information, or to make connections between facts using critical thinking skills, or, even better, to do both at the same time.
Sean, EssayForum.com