Genuinely tough choice, but I had to vote GT even though I'm not a fan of the large running pony. I'd much prefer a tri-bar emblem in the middle of the grille.
Second choice would be the Pony Package and it's nod to Mustang history.
If the Boss 302 grille had fog lights instead of dummy openings, that would be my fave by miles and miles. As mentioned I like a tri-bar emblem in the middle of the grille, and I much prefer the grille surround to be painted body color, as on the V6 cars. In fact this is the look I'm going to go for on my car, if I can just figure out how to marry the GT fog lights to the Boss grille.
2012 GT Premium Coupe | Performance White | 401A Charcoal+Grabber Blue | Comfort Pkg | MT82 | Boss 302 Shift Knob | 18" Pony Pkg Wheels w/Brembo Pkg Center Caps | Boss/CS Front Valance | Scott Drake 5.0/Tri-bar Fender Emblems | FRPP Strut Tower Brace | Redline Hood Struts | GT500 Rear Splash Guards | Rear Spoiler Delete | Sound Tube Delete