I'd go with the 2017 I think....but I'd be curious see your total cost, including interest, on both options, less what you think the cars are worth 5 years from now. I bet the actual depreciation on the 2017 is a large chunk of your discount, and the 5 year "total cost" might be relatively close.
FWIW I bought a 2011, as new, in spring 2012 and combined a serious break on the price with whatever the current new car financing rate promotions were....1.9% I think. Anyway, at the time my "leftover" was as cheap as a 1-2 year old CPO in terms of cost of ownership.