Confusing, right? For the purposes of this article (and your sanity), I'm limiting the buying-guide analysis to the Non-Phone iOS gadgets: the iPods and iPads. It used to be that there was a huge gap between the 3.5-inch touch and the 9.7-inch iPad. Now there's a spectrum: 4 inches, 7.9 inches, 9.7 inches.
So, let's look at each one, starting with the newest.