The 17 pounder on the firefly had a comperable performance to the 7.5cm KwK L 70 main aramenent of the Panther. The Panther howeaver had a much heaver and well sloped armor. The Panther was a better tank over all compared to the Tiger, and the King Tiger was the Most formadable of all, howeaver the Panther possesed a better balence of spead armor and leatheality.
In general one can say the Sherman was a reliable,mass produced way to get US tankers in to combat so they could make the ultimate sacrafice. I read whear it generaly took 5 Shermans to every Panther.
Comparing the Sherman to the Pzkfw IV is howeaver a diffeerent story. The MA on the German Pzkfw IV, the 7.5cm KwK L 48 had a comparable performance to that of the 76mm Sherman MA ( not the 75mm, it was superiour to this gun) the armor protection on the Sherman and the Pzkfw generaly speaking was about even, that is to say each could kill the other with out to much dificulity. the Sherman howeaver was a much bigger target.
This general comparision does not factor in the Jumbo, or the British firfly.
As I have stated above, I think that the Sherman would be a logical addation as a next choice for a GV, it would be a good match aganst the Pzkfw IV, and it has a decent AA MG, It would be nice to see a British paint Job though.
I hope that at some point we could get a Soviet tank, the T 34 did more to end the war than the Sherman did, it howeaver has no AA gun
It is good to want our favorate rides but I think we (I) nead to be objective about what we try to back for addation to the MA.