The tank was part of German corps during the Invasion of Poland on 1 September 1939. Panzer IV became the most widely exported tanks of Germany. It was part of the German forces in all combat theaters. Throughout the war, the design of Panzer IV upgraded extensively to become more powerful and counter new threats. It was the only tank to remain in continuous production all through the war. Due to their continuous production and mass built, they were extensively used throughout the war by the Germans. The Panzer IV was an in-service German medium tank from WWII. The production of KV-1s was stopped later in the war. These tanks were expensive than the T-34 tanks and the T-34s performed better. Until the Germans developed a better gun to tackle the KV-1, these heavy tanks were invulnerable to any German weapons except the 8.8 cm Flak gun. A single KV-1 with some infantry support was enough to tackle large German formations during the war. They were known for their heavy armor protection and were effective during the earlier phases of the German invasion of Soviet Union.

They were used by the Red Army during WWII. These tank series derive their name from Soviet defense commissar and politician Kliment Voroshilov. And pick one with a good heater to keep the crew warm in the drizzle.The Kliment Voroshilov (KV) tanks were a series of Soviet heavy tanks. That would give some edge in letting you open fire at longer ranges than the opposition. If it's definitely going to be poor weather then probably a German tank since they tended to have better optics. I think it's a case of 'what exact job do I want it do, at what time' - and then close your eyes and stab at the selection Tiger II was too large to be a viable tactical vehicle, IMO, but I'm sure somebody will make a good case for it. Centurion because I'm a Brit and they were very upgradable. Panthers were good tanks, but T-34/85 were far cheaper (given the Soviet manufacturing/ costing system).

Stalin tanks were too heavy for my taste, with (in JS-III) limited ammunition. If early WWII I'd go for T-34/76 (a lot wouldn't), late WWII I'd probably go for T-34/85 or Panther. Okay, what is the likely opposition, what is your military budget, what is your maintenance service like, supply train, level of crew training, expected combat range, support structure, tactical doctrine etc? What date?

Best battle tanks of ww2