Kid in a candy store with those choices. There isn't a bad one. I had to go with the "R" as it was over the top in 2000 and who would ever have thought $30000+ for a Mustang? Ya, like that would never happen.
I had to go with the 2012 Boss 302, sipmly because of the strides Ford made in the over all handling of the car. I've read that it is one of the best balanced Mustangs ever made, and I'm a sucker for hugging corners