The Shelby, no question about it for me. The Charger is cool and pretty tough looking, my buddy actually has one, but in my opinion you just can't beat the looks of the Shelby. Plus A Shelby can actually handle, something very difficult to get a Charger to do. There's also a plethora of aftermarket stuff for classic Mustangs. Besides, who cares what stock times were? Stock drivetrains suck for Hot Rods or toys.
But even dead stock vs. dead stock, I'd pick the Shelby.