I think 1971 is the coolest year. It would need to be equipped with the 2.0, manual transmission, and whatever differential option provided the fastest acceleration. lol
Being the first model year, the styling is in it's purest form. It's the closest to what the designers originally intended the pinto to look like.
'71 cars have less pollution control equipment and higher horsepower ratings than later cars. They were also lighter (although structurally weaker) than later cars, therefore the best performers in stock form.
Also, I'm willing to bet there aren't a lot of survivors left from the '71 model year, so to have one would make it that much cooler!