On the GEN5 I like the 2010-13 much better then the 2014-15. To me the tail lights on the 14-15 look like they came out of a old nova from the 70s and the one vent centered in the hood just don't fit the car.. That is JMHO
My vote is 2010-13 and 2016-17
Since I owned a 2011 SS and now have a 2017 SS I might be a bit bias