I just happened to catch this ranking on Discovery Turbo and some of the boats mentioned might interest you.
The one's that relate to us are:
5th Place - British T Class
4th Place - US Gato
.
.
1st Place - Ger Type VII
The ranking was based on:
Production Ease
Terror Effect
Weaponry
Overall Effectiveness (read tonnage sunk)
Range
Length of Service
While I concur that none of the boats above are actually proper submarines do you agree with the ranking's assessment of these boats?
Discuss.