Funny thing - when the 13-14's came out, all the 11-12 guys were happy they had theirs and wouldn't have dreamed of trading it in on the newer one. The differences between the 11's and 13's are minimal, and the improvements marginal, if any. At least the 15 is an advancement in technology.
I still find 11-12 the best looking one yet... (that includes 2010 too, but without the 5.0 it's a little 'eh' IMO)
I am hoping the 2017 refresh looks a bit meaner/sportier and less tame...