I went from a supercharged 03 gt to a 2014 5.0 and haven't looked back. It's a night and day car, from both exterior looks, to interior to drivability. I liked the look of the new edge, but love these new interiors a lot more. Personally I like the look of the 13-14 better than the 11-12, however it's more of a personal preference. There are a lot of good looking 11-12 out there, including a bunch on this site.
2014 Mustang GT
Flowmaster American Thunder A/B, BBK X Pipe, BBK cat delete pipes, 20" Vossen CV5, Eibach Sportline springs, Koni Yellow, BMR Adj. Panhard, Vortech V3, ID1000, Roush BAP, JLT Intake, Lund Tuned