iPad mini with Retina Display
The smaller of the two iPads, the iPad mini with Retina Display has the same specs as the iPad Air put into a smaller shell. With a starting price point of $400 it's the better option for those on a somewhat tighter budget. The smaller screen makes the iPad mini with Retina Display better suited for one-handed reading or for those who want a tablet they can carry around in a smaller purse or bag.
The iPad mini with Retina Display is just as capable of replacing a laptop for many people as the iPad Air, if they can deal with the smaller display. It might be easier to carry around, but it's slightly more difficult to type on because of its size.