I have the 8gb MBA, although in my case it's simply down to cost. On the basis of future-proofing, I would not recommend 8gb to anyone, and find even with my relatively light-moderate workflow that my system is regularly utilising swap. While mine was only ever intended to be used as a secondary machine for when I'm not at home, I have since switched to using it as my main machine as I've had some hardware issues with my main build. Either way, go for the 16 at minimum.