First of all, I'm going to be programming in college. Half of my course is Windows-only, but I figured for the specs it runs on, I'm getting better value hardware-wise compared to any other ultrabook. In fact, it is the best ultrabook in every way; battery life, graphics, slimness, power! I have yet to find an ultrabook on the PC side of things. Plus you get the best of both worlds with bootcamp.
I don't see the point of getting a Surface Pro 3 or Lenovo Yoga 2 Pro because they're more expensive and/or have worse specs (battery). Surface does have a pen and all but it's got throttling problems and significantly less battery.
So it all came down to which MacBook to get. I personally find the MacBook Pro overrated. It has the retina display, but even though people swear "It's a must!" and blah blah, I don't care. I was fine with my screen before the Retina display existed, don't need it now. Unless you do photography or anything visual on your MacBook, you probably don't NEED the display.
Next I considered performance. Despite what one might think, a college student programmer probably doesn't need an i7/16GB RAM/dedi graphics. Running Visual Studio is fine on my old laptop, so it'll do just fine on a fancy new ultrabook. I determined an i5/8GB RAM/256GB/Intel HD 5000 laptop would suit me just fine. I might get i7, but again, it wouldn't be necessary. I don't need to play games, because I should be doing homework anyways. I'm also not doing 3D stuff.
Back to screens, I also wanted a mid-size screen. 13.3" suits me fine. A slightly higher resolution than 1366x768 makes it less claustrophobic. I'm one of the few people who don't want a huge screen for programming. I've been programming already for a few years so I'm not ignorant. Mac OS X has multiple desktops and easy swipe gestures that eliminate the need for more screens anyways. If I need to see two things at once, I can use my tablet to look off anyways.
In terms of portability and battery life, I wanted something slim and light and something that could last a minimum of 6-7 hours DOING more intensive work. SP3 does that much on light browsing.
And so the choice was clear, I wanted a MacBook Air 13".