Since the first criteria is being undefeated, its between Gavin and Dlagnev. I feel that Dlagnev is the best heavyweight in the country but because of injuries he missed out on potential matchups with Bergman and Fox(who he dominated last year). So that hurts his case and leaves it to Gavin. Metcalf would be third because of his dominating season but he won't win it because of the one loss even though I would like to see him get it.
Pucillo isn't undefeated, he was pinned by Tyrell Todd of Michigan at the Cliff Keen tournament. The results were only thrown out for seeding purposes and the results still count on their win/loss records. So Pucillo has one loss on the season. The reason the results weren't used for seeding purposes was because the tournament organizers didn't hold proper skin checks for the tournament.