United States of America
During World War 2, the United States was the strongest economy with capabilities of mass production due to Henry Ford which introduced the use of mass production and assembly lines. Due to this reliance from allied countries they needed to produce a tank as a stop gap from the ever increasing German Threat. This presents the major issue that the United States was fighting a war across the ocean. This prompted the motives of building a tank that will last and not easily break in the foreign country. So they produced the Medium M3 Lee which has everything a tank needed to be good but it came out all wrong. Although the weird design of the tank and the pretty obvious cons of it being tall it created the necessary stop gap to create a better tank that the Americans will later release near the climax of the war.
The Sherman can be considered on of the best all round tanks with high mobility and decent firepower. It was a very reliable tank for its time. The American motives for tank building can be evident here as they focused on creating a reliable and all round good tank as creating a specific tank for a task would be too difficult to ship across the waters. As the Atlantic was constantly being patrolled by German U-Boats and it would be too costly to create multiple tanks for multiple tasks.
One other strategy was numbers, because of America's economic power and ability of mass production they would keep making tanks and overwhelm the enemy. Even with German tanks being superior then the Americans they had tons so one loss would not mean much while Germans losing one would hurt their military power.
Russia, having a range of great tanks built in the course of the war their motives can be seen as wasteful or efficient. With the amount of manpower that Russia held they could crew many tanks and similar to the Americans overwhelm the enemy with just sheer number. But they did not have the same economic backbone of the Americans and could only build so much. However, they did not have the weakness of having to fight a war so far away, because they were already so close to the battle. This promoted them to build tanks that were not reliable but simple. One crew can be easily thought the design of the tank and replace any part were broken. Bring up the motive that the tank was gonna break anyways so why not make it easily fixable. Although this method was crude it was efficient. Although they did not make reliable tanks they made good tanks.
The T-34 was a very good armored and well fire powered tank. Which could match early tanks that the Germans produced. With the thickest armor being 60 mm with a 76.2 mm cannon with later upgrades giving it a 85 mm cannon. With over 22,000 produced over the course of the war.
Germany's tank developed nearly evolved with its main battle strategy which was blitzkrieg. But later as the war grew to a stalemate they would try to create more powerful tanks to mainly scare the enemy force. Although Germany did not make many tanks they made many tanks that were considered the best of the war. With the picture above showing a Stug III which was a very good tank destroyer being responsible for over 20,000 Allied tank kills. Although each tank that the Germans made had its shortcomings the German were well known for their tanks and feared by them.
The Tiger II is considered to be the best tank of the war after fixing the flaws of the Tiger I. Having advanced sloped armor with thickness of up to 185 mm and a 88 mm cannon. Although it had a limited spotlight due to its late introduction into the war. With only 489 made, but commanders like Kurt Knispel showed the absolute power of the tank scoring over 168 kills becoming the highest scored tank commander.