The MP-44 is a full auto weapon so it is not on the same page as the other rifles we are talking about. Additionally it was only used at the end of the war 1944-45 and the majority of German infantry were still carrying Mausers.

But yes if I had to pick up any of the guns off the ground in WWII the MP's from Germany might be the best choice. It heralded the future of military weapons. You can see the DNA of both the AK-47 and M-16.
Awesome gun for sure.

As for an armed populace detering invaders; maybe it won't actually deter them from invading but they will regret it eventually. Yes many would die but that is not the point. American's, who enjoy being free and are gun owners would not stand idly by and let an invading force occupy our land without a fight. And yes if the time came many of us would yell; "WOLVERINES"