Most Popular iPad 2 Model Is Also the Most Expensive
Apple offers six separate models of its iPad 2 (nine if you count both CDMA and GSM 3G versions), but more than half of buyers choose between only two options. The 64 GB 3G iPad 2 and the 16 GB Wi-Fi model are the consumer favorites.
Source: http://gigaom.com/apple/most-popular-ipad-2-model-is-also-the-most-expensive/