Tough call. Both are nice cars...but if I were you, I'd get a 2014 in a few months when they'll be super discounted to make way for the 2015.
I have a feeling the 2015 and the 2017 will be two totally different cars (new Transmission, engine choices,, power increases...)...so it's best to wait.
2012 Mustang GT Premium
BLACK on BLACK 401A. A6, HIDs, Security, Rear Camera+Reverse Sensing, Remote Start, Comfort.
(Planning on CAI/Tune then I'll be good)