Out of tanks, I have to nominate these three:

PzKpfw V Panther
It was a good all-around medium tank, with fast speed and a high-velocity cannon. It was also easier and cheaper to produce than the heavy Tiger tank. I would call this the best tank of WW2.

T34
Also a good all-around tank. The T34 could be massproduced, had a good speed, a good cannon and it could also be modified; in 1944, with the arrival of heavier German tanks of the types PzKpfw V Panther and PzKpfw VI Tiger, the T34 was upgraded to carry an 85mm cannon, which was capable of battling both of these German tanks effectively.

Sturmgeschütz
The StuG assault gun -especially the StuG III ausf. G- was one of the most cost-effective German weapons. Being built on the PzKpfw III chassis and later the PzKpfw IV chassis, it was cheaper to produce than the PzKpfw III and PzKpfw IV respectively. It was especially priceworthy constructing on the PzKpfw III, as the chassis of the PzKpfw III normally -if not always- carried a 50mm gun, which started to become obsolete already in late 1941 on the Russian front, with the arrival of the heavier T34 and KV tanks. The StuG, however, had superior firepower over the PzKpfw III with its 75mm gun.

/Kommando