Ipad air vs ipad mini 2
I'll stump for the Air here even if you need portability. I came from an iPad 3 and the original mini. Got the 3 on launch day and loved it, but it was just too cumbersome to lug around in my bag to and from work every day, so I picked up the mini when that came out. I happily toted the mini everywhere and fully expected to upgrade to the retina version when they announced it. Strangely something in me decided to try the Air as I really did long for the bigger display and I thought with the change in form factor and weight it might be more viable as a commuting companion. Turns out, for my use-case, I was right. Slimmer and lighter has made the full sized iPad far more portable than the older models. Fits perfectly in my small commuter bag, doesn't weigh me down at all, AND I get the nice big display. It's like having a quasi-laptop with me at all times! Best iPad ever, IMO.
This is, of course, my opinion. There are many reasons to choose the mini, but in my situation the Air is the clear winner.