Me? I've already got the pet I've wanted since I was a child - my german sheppard. I had one when I was younger (course, she was only like 1/2 sheppard), but we had her put down because she had kidney failure. Sucks... but she was in a lot of pain. That was like 11 years ago though.
I would enjoy having an overgrown tuatara around, just to watch its third eye >.<
But in reality, I would probably just stick to a dog/cat (that means either a dog or a cat, not both in one), although it would be great fun to own a penguin haha.