There were different scenarios for tanks:
1. Break through the defense
From Guderians original concept this was not the job of the tanks but of the infantry. However, the longer the war took the more tanks and Sturmgeschütze were involved. The Brits had a different point of view and so they had the class of Infantry tanks.
2. Fight enemy tank concentration
3. Make trouble behind the lines
The most important one in the Blitzkrieg conception. Move fast, destroy all supply, command and artillery units behind the enemy lines.

To solve all these tasks a good mix seems to be the optimum. Shermans and T34 were good enough to support the infantry attack. German Sturmgeschütze too. Fighting enemy tanks a some heavy tanks can be helpful. But German Jagdpanzer and mobile Antitank guns would be also sufficient. To rumble behind the lines the T34 was also very good. It was fast and strong enough to break some resistance. And with its big numbers he was able to appear art many different places. One problem with German superheavies was that they consumed a lot of fuel with a relatively small tank. So their range was limited.