The Kimberleys and Uluru are pretty unique. I'd rather visit them than man-made attractions. As far as animals go it's a toss up between the wombat (cute and chubby, kind of awkward-looking but boy, can the run when they need to) or maybe the platypus, one of the weirdest little mixed-bags I've ever seen. Misleadingly cute but they can do some damage.
But then again the echidna is also a fascinating little bundle...and the bilby.
Come to think of it, they're all pretty adorable. Not much help, am I?