I like the portability of my mini but just purchased an iPad Air 2 for the larger screen size. I love the larger screen. I too wish the iPad Air 3 was available. The Air 2 I just purchased was from BB for BF with $100 discount so that made the sale.
I really love the larger screen. The Air 2 will be for home use. Very nice device.
The Mini 4 is the first iPad I have enjoyed so much I missed it when I foolishly returned mine last week. After the current iPhones did not work for me, I exchanged my 6s+ for a 5s and another iPad Mini 4.
I love the Mini form factor. Being able to read on it is wonderful. Movies are awesome, and I'm even getting used to typing on the keyboard one handed.
The screen / speakers / weight are great.
It completely changed my mind about iPads.