This makes me feel like a fanboy (it's also like asking a parent what child it likes most). The key to Apple's success has been its iconic designs and that design ethos, with the exception of the dark period of the nineties, has led to so many designs that are unmatched in terms of sheer numbers by any other consumer products company. The fact that we can all make valid arguments as to why one design should be considered the best only emphasizes the ability of the Apple design team over the years.
All I hope is that they can keep it up and I look forward to the magic of the redesigned Mac Pro.