Crew Comfort - Soviet tanks are not known for crew comfort, period. The cramped designs did not take crews into account other than as necessary pieces of the machine. Height restrictions limited who could serve in the tank corps. The Sherman was typical for the time period.
Combat Effectiveness - this can and should be judged in two ways. First, the basic machine itself and second how the armies used the tank. The Sherman was intended to be an all around infantry support weapon. Tank Destroyers and towed anti-tank guns were the principal weapons to combat enemy tanks in the U.S. Army. As such, the Sherman had a lower velocity 75-mm main gun, with a very effective High Explosive (HE) shell. It often came off second best to contemporary German tanks (Panzer IV and later), but was good enough when properly employed. Later variants added a better tank dueling gun and ammunition (especially the High Velocity Armored Piercing [HVAP]) which gave the Sherman a better chance against late model German tanks.
The T-34, in 1941, carried a very powerful main gun that penetrated most German tanks. The offensive nature of the Soviet tactics meant that the low profile and low ground pressure made it a hard target that could go anywhere (it seemed to the Germans, at least). The low profile worked against the T-34 in defensive situations, though, making it hard to depress the main gun from high ground. The T-34 was designed to spearhead the offense, and was fast and hard hitting in ways the Sherman could never be (even with the Sherman's speedy powerplant). Thus you have an all purpose tank meant to accompany and support infantry assaults versus
