Sherman M4A3E8 and Firefly were the best Sherman. For its time the 75mm Sherman was decent enough, but past 1943 onward it was pretty bad. While the T-34 is good, its overrated as the unstoppable medium tank of the war. Soviet tanks designed prior to the T-34 were pretty bad(see T-26, BT-5, KV-1).
In the Korean War the M4A3E8 Sherman and T-34/85 were pretty much equals, whoever shot first won. With the new American Pershing tanks, there were reports of the tanks over penetrating. American soldiers said the 90mm gun would punch through front and back and the shell would go into a hillside.
also you should rename thread to tank discussion thread