I deliberately skipped the iPad Air 2 because I've had an Air 1 since launch day and it was still doing everything I needed of it. I was slightly jealous of the thinner design and the gold colour option, though. But now the main thing I'm noticing is the lack of RAM, mostly because I'm doing a lot more photo editing on my iPad using apps such as VSCOcam.
My main hopes for he iPad Air 3 are more RAM and force touch, probably better graphics too. I think the physical design of the device is in a pretty good place right now but I really wouldn't mind if Apple wanted to push boundaries and make it even thinner, if that's even possible or practical. Either way, I've loved my iPad Air 1 but I will be preordering the Air 3.
Ps. If the rumours of a black and gold iPhone 6s are true, I'd like to see this colour combination available with iPad too. That combination is my only excuse for buying the next iPhone, right now. So I'd like an iPad to match.