I would go with the size of the iPad Air or iPad Mini w/ the same specs as the iPhone 5s (unless Apple dramatically switches things up with the iPhone 6, then it would be those specs). I just want a gold iPad Mini (retina) w/ touch ID.
Touch ID in the gold would be cool. Also would be curious to see what apple could do in the way of a keyboard. I know we have 3rd party alternatives but a Smart Cover with keyboard would be cool.