Look at all these in person, carefully.
I did exactly that yesterday, with particular interest in the Air, wishing to examine its screen more carefully. You may not care for the Air, although decidedly the lightest of the bunch if continually carrying it as a student. Also consider if really wishing an internal optical drive, as the RMBP does not have one either.
At first glance the MacBook Air screen looked perfectly fine, and with no other comparison one might be satisfied. But in direct comparison to a 13" MBP it was definitely lacking, appearing somewhat washed out in comparison the MBP with richer color saturation. The Air is often cited as superior, as having a higher resolution than the 13" MBP, if obviously other factors come into play. Either would do, part of this personal preference, but all pale in comparison to what the RMBP offers. I looked closely between it and its cousin of a 15" MBP, exact same images, and the RMBP is clearly richer with visibly crisper detail. If your only criteria in a notebook is the quality of the screen, there is only one choice: the RMBP.
Something else of interest as well. In comparing a 13" Air and MBP side by side, their respective speeds were clearly evident. The Air was responsive, just doing as asked. But the same motions, opening software, etc. on the MBP came as a surprise. Even though knowing it would not share the same SSD as the Air, it was still surprising how slow it was in comparison.
As the RMBP has the same flash architecture as the Air, it is as responsive, and even more so in being significantly more powerful. One could certainly live with a traditional HDD, but if the least impatient then it would make a big difference, if opting for a MBP, to update it with a SDD.
Plan on that in advance, and the price tag begins ratcheting up. A 13" Air (2.0 GHz / 8GB ram / 256GB flash storage) is $1,700. A similarly equipped 13" MBP (with slightly faster processor) is actually $100 more. One could cheap out and save some on having only 4GB of ram (probably not advisable), or be extravagant in upping flash storage to 512GB for $500 more.
If weight some consideration, then as said the 13" Air decidedly lighter at 2.96 pounds. Tack on about 1.5 pounds more for the 13" MBP, at 4.5 pounds. Surprisingly, the 15" RMBP weighs in slightly less, at 4.46 pounds. So roughly comparable, although obviously the RMBP a bit more bulky. At least in width and length, but appreciably more thin. Do not discount that; it can seem decidedly more svelte than the MBP models (those more like bricks in comparison, even the 13").
One will have their own opinions. But whatever yours are may shift once having examined these various models side by side.
- ps. A 13" RMBP is surely on the horizon, as the current 15" RMBP points the direction Apple is headed. It may arrive this autumn; or easily only materialize a year on.
Moreover, possibly a very questionable purchase if Apple does not seriously upgrade its power to compensate for that drawn by the retina screen. The deficit most significantly with the GPU. To date the 13" models have always been left the poor stepsister in this; being one reason even now one might to consider a 15" MBP or RMBP, if concerned with such a factor.