I have both the latest MacBook 12 and also the latest Pro. I would have to say that if typing is the number 1 feature, the keyboard on the pro is just spaced ever-so-slightly further apart and offers a more error-free typing experience for ME. You have to go into a store and just type on them to get a good feel. Having said that, I LOVE the fact that the so-much-smaller-and-lighter 12 is INCREDIBLY easy to carry around EVERYWHERE and GETS THE JOB DONE. Both have the Retina display which, for anyone whose eyes get fatigued by staring at computer screens (you said you were writing your thesis, right???) then make sure you get the retina screen. Otherwise the AIR Is a fantastic option if you can live without the retina screen but the keyboard on the pro still rocks. My quasi-daughter-in-law is a contract editor and hits the deadlines with her MacBook 12.
Hope that helps.