Federico Viticci on why he likes the iPad mini better, includes this bit in his article:
You don’t hear people saying that, because of the size differences, the 13-inch MacBook Air is for consumption and the 15-inch MacBook Pro is for creation.
Viticci’s post is really solid, but this is a really odd point. It’s odd because the better analogy is the 11″ and 13″ MacBook Air. Those two really mirror the iPad (and the coming Air) and iPad mini situation better, where the smaller is (seemingly) a lot more popular, but for many the slightly larger 13″ screen is likely the better option.
My assumption is that most people aren’t going to buy both, and are likely to use the iPad a lot, and given that assumption I still think he Air will be the better option (just as I would recommend the 13″ MacBook Air). If you want a smaller screen for portability, the iPhone 5S is the best choice.