On paper, the only category where the American subs came up short is in the depth rating. The Germans could go 160M easy. The newest American "thick skins" could only do about 100M in the Gato class and 130M for the Balaos'.
In the general discussion section a month or so ago, I learned from others that due to a shortage of raw materials, namely copper, the Germans were forced to use an inferior direct drive propulsion system that was prone to failure. The American subs diesel engines drove generators which either drove electric motors for propulsion or charged the batteries. The electric motors drove the sub whether it was surfaced or submerged.
I also read somewhere that the Germans didn't expect the war to last but about 5-7 years and engineered their subs accordingly. The Americans from the O class on up shot for a life expectancy of 20 years.
I don't know how the British or Russian subs stack up. I'm sure others here do!