iPad Air 2, I used to rock an iPad 2 but unfortunately it died from water damage around 5 months ago.
Heck, we still have 3 64GB iPad 3s in the house (parents and brother) that are running on iOS 6. If there comes a time that the apps they use start requiring higher than iOS 6, that's when the iPad 3s will get replaced (likely with a refurb 1 gen old device). The iPad 4 was considerably snappier than the iPad 3 on iOS 6 and I definitely experienced some slowdown and stuttering going to iOS 7 (with both 4 and Air) hence the decision to keep the 3s on iOS 6.I can't give up the space on the iPad3 but it is showing the processor getting to be dated running iOS7 and I've hesitated to go to iOS8 with it.
Im actuallu really surprised by this poll. Usually the cheaper product sells more, but there must be something so compelling about the bigge iPad's screen size for people to disregard price and opt for that one.
I'm loving the hell out of iPad 4, still. It's my favorite chassis. And the Air doesn't have leather Smart Cover.
I'll upgrade when something significantly different happens. Either no home-button or auto-stereoscopic display or bezel-less 12" screen.