Bought the Air 2. It lasted like 2 days with me before I couldn't justify what I had spent on it. It's literally a huge iPod Touch and it has some fundamental issues:
1. Thin is not in, at least not without some ridiculous concessions. The device vibrates like a tractor when when watching video or listening to music through the speakers... or emitting any sound, really - even ringtones, and even with an Apple Smart Case on it. It's just unacceptable, and makes it feel like a cheap Samsung Tablet from 2012. If you are thinking about getting this tablet, go into the Apple Store and play some videos or music on a display unit on high/max volume and make sure that is something you're going to be able to put up with.
The speaker position is also pretty bad, as it's hard not to muffle them when watching video in landscape orientation.
2. The Screen Aspect Ratio is off for Video. Portrait or Landscape, there's always black bars and those are never attractive on LCD screens - especially when auto brightness ramps up. I kind of feel like if you're going to go with 4:3 on a media-centric tablet, AMOLED is the way to go.16:9/10 is optimial for LCD screens (that's just my opinion, I don't read many books and webpages are just fine at the other aspectratio).
3. Poor use of screen real estate. The Home Screen is 4*4 with Dock when it should be 5*5. Lots of apps are just poorly designed for a screen that large with that resolution. Should not have to exit out of Now Playing to see the track list for an Album in the Music Player, for example. There is more than enough room and pixels for that all on the same screen. They should use Google Play Music on a Nexus 9 to see how to design a more usable/efficient media player UI/UX. The iPad basically gives almost a replica of the iPhone UI blown up to 9.7".
I think Material Design looks horrible, but they did do a good job at optimizing their OS for larger screens with it, moreso than Apple with iOS (3rd party devs are a different story, however).
4. Had issues with apps freezing. Not freezing the device, but going unresponsive for several seconds at a time. Has to be something with the device software itself, because that never - ever - happens on my iPhone 6 Plus.
5. Needs split screen multi-tasking. At that screen size, it kinda needs it. It's not a very productive tablet to use without it, especially with how inflexible sharing is in iOS. Using Dartfish Express or Coach's Eye, I found myself wishing I could analyze in the app while taking notes in OneNote docked to the other side of the screen (something a Windows RT Surface or Samsung Tablet can do with ease).
6. Frankly, unless needs are very light... This thing can't even come close to replacing a Laptop. It's basically an iPod Touch Air 2...
So I got the 13" MBA. If I decide to get a Tablet, I'll pick up the Amazon Fire HDX 8.9 16GB. It has a better Camera [and with a Flash], much better battery life, and a better screen with better screen aspect ratio than the iPad for video, at significantly lower price - and is backed by a great media ecosystem. It doesn't vibrate wildly when it plays any sound. I don't care about Apps much on a Tablet, and I don't really need that much storage, my iPhone has 64GB.
If I ever feel I need a big screen iPhone or iPod, I'll get an Apple TV for way less and just mirror it to my HDTV instead, Lol.
I never considered the Mini 3. TouchID isn't worth an extra $100 and the hardware in that device is aging.
I'm starting to feel like the laziness of Android Devs is helping Apple more than anything in selling iPads. Because so many Android apps are Tablet-optimized and Devs are dragging their feet, it sort of keep the iPad up there as the best option for a Tablet, generally speaking, right now. If Android had the Tablet-Optimized App Ecosystem than the iPad has, it would be extremely hard to justify paying 20-50% more on an iPad compared to something like an Amazon tablet.
On the flip side, this also gives them time to get the productivity features implemented. It's like the two OSes are strongest in the main weak point of their rivals.