Hello! I love listening to the iMore podcast every week on the way to work! This competition is an awesome addition to everything else you guys do! I would probably go for the iPad Air 2 as I still have an iPad 2 and the poor thing is getting old now!
Also, did you know that Apple now offers international payment on local Apple Online stores - so you can order a gift (or prize) for someone in the Australian store, for example, but use an international billing address and payment method (I thought I'd mention this as it may help international prize winners with compatibility issues). Merry Christmas!.