Depends totally on locale and availablity.
Fact: GT500’s actually have nothing to do with Shelby or his plant. They roll off the Ford line and go to dealerships, just like regular six-bangers and Mustang GTs. The Hertz GT-Hs (and I think the Shelby GT, not GT500) are sent to the Vegas Shelby facility and are hopped up there with suspension goodies and such.
The debate is that one is a “true” Shelby while the other is a badge job and is really an SVT without the SVT badges.
IMO the last “true Shelby” was the '66 model. In '67 Ford started taking over the conversions and by '68 they were made in Michigan, not Cali.