Why must I have to choose only one? Arrg! I'm horrible with choices.

I picked the Aussie Kooks. The early years are alright, but the recent years have been IMO stunning. I especially like the 2008. The bird has the most mischievous expression on his face, with his head cocked right at the person looking at the coin. I find it charming.
I also love the classic look of the Canadian Maple Leaves, and I really like the direction the Chinese Panda coins are heading as well. That thick rim framing the coin, with the legends over it remind me so of the 1797 copper cartwheels of Great Britain. I find that look very pleasing.