Skylake is so much more optimized, energy efficient (so less hot), and newer. Newer might seem like a silly argument, but don't forget the upgrade possibilities you have, and the newer standards for USB, SSDs and RAM (to name the most obvious ones) you enjoy with Skylake. If the price difference is not something you are really worried about, definately get Skylake.
There's a lot of buzz around how old I7s still hold up (and they do, performance wise), but power efficiency, a more silent system and the new standards for essential hardware are worth it. Skylake is dropping in price, you don't really pay the early adopters premium anymore (dependiing where you are from), and it's just so much more convienent.