Probably New Zealand. New Zealand is made of two islands, and they’re really far away from other countries like Australia. That means that the animals living in New Zealand have been separated from other groups of animals for a very long time, and makes them especially weird!
In particular, New Zealand had no native mammals (except a few bats). The only mammals living there now have been brought by humans in canoes and ships. So instead of mammals coming to dominate the wildlife, birds are the most important group of animals living there.
My favourite New Zealand bird is the extinct moa. Some people think it was the largest bird ever to have existed, and it was definitely much bigger than a modern ostrich.