I personally like the 2013 rear end better so I say 13. Looks are subjective though. If you like the look of the 14 get the 14 as it is newer.
I would think the deals should be better on a 13 but have not been looking at pricing since I bought mine. I got supplier price on a 13 last summer so seems like should be able to do better now.
2017 zl1 or GT350 hmmmm
2013 ZL1 -sold
2013 Megacab 8" lift 38"mt's