It's a tough poll. The Vette and the Mustang really don't compete head-to-head and the poll asked which one had the most impact across the board. Even being partial to the Mustang, anyone that looks at the true meaning of the poll would have to choose the Mustang over the Vette. The Vette has always been much more of a niche vehicle due to its high cost. The Vette did not create a segment. It was Chevy's answer to European sports cars. The Mustang created the classification of "Pony Car" and spawned a whole new generation of cars. If not for the Mustang, we may never have had the Camaro, Firebird, Barracuda, AMX, etc....
This is not a knock of the Vette. If I could afford a ZO6, one would be in my garage today.