Judging submarines by doctrine and operating theater

Which navy built submarines best suited to the tactics and missions they actually used during the Second World War?

There is no universal winner: British ocean-going boats were awkward in the Mediterranean, Italian boats suited that sea better, and German or American designs are stronger candidates when matched to their intended missions.

There is no single best submarine without specifying the boat, date, mission, and operating area. British T-class and related boats were designed with large oceans in mind, which made Mediterranean employment a poor fit. Italian submarines could be more appropriate to that enclosed theater, while German and American boats performed effectively in roles closer to those for which they had been developed. Doctrine and geography matter more than a simple technology ranking.