Hello, Die Nibelungen - a very warm welcome to these Forums ; and thanks especially for such a well-phrased posting.
I certainly shan't argue with you over the A-bomb; logically, you've an excellent point.
As an aside re smallarms, 'best' itself can be endlessly debated. So much depends on the context in which the weapon saw action. If one fired a PPsH41 under range conditions today, I'm sure it would be quite inaccurate and feel very crudely-made to boot.
But under Eastern Front conditions, the crudity and simplicity of the gun meant that it went on firing whatever happened. The relatively sophisticated feature of the chromed bore was clever - the average 'Ivan' rarely cleaned his gun. And the huge drum magazine was extremely handy in close-in combat conditions.Plus it was simple to manufacture.....
So given it's context, it probably was the best smallarm.
( But I'd still prefer the MP44 !
)