This would be a great comparison, but all of the ads conveniently neglect to mention that as configured the MacBook Air 11" is cheaper. Moreover, for $70 more than the configured price of the Surface, you can get a 13" MacBook Air which has a bigger screen.
The only advantage the Surface Pro 3 has is touch. I'm a programmer, my bash shell [defecates] on laptop touch interfaces. It was never meant to be, the Surface Pro 3 is only one step beyond this,
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and this sucks, though for the price, it's probably still a better machine than the Surface. At least it sits on your lap, dammit.
If you really need the touch interface, buy a MacBook Air 11" and a Wacom. It'll be a better overall experience for only slightly more than the price of a Pro 3 at entry level.