which to buy:ipad mini 2 or ipad air? quality wised which is better?

before Lollipop, I would have asked it you were sure you didn't want a Nexus instead

Ipad mini 2 for the lower price but for the same amount of memory. (16,32gb both)
ONLY difference of the two is that the screen between the 2 is that the mini 2's screen looks better by a difference of 326 ppi to 264 (Pixels per inch).

They are the same thing. Only difference is the Size
if you want something smaller go with the mini. But if you want something big then go with the Ipad air

I pad mini is the best.