I was surprised to read that the most popular model is not the 32GB. I would have thought most would play it safe and split it down the middle. Instead most people either buy all or nothing. The 16GB Wifi model was the most popular followed by the 64GB Wifi.
http://gigaom.com/apple/most-popular-ipad-2-model-is-also-the-most-expensive/
http://gigaom.com/apple/most-popular-ipad-2-model-is-also-the-most-expensive/