One thing that I noticed in this forum was that people are considering which tank is the best vs which one is more important. As much as I love the Tiger, the Sherman was probably the best of this list. It was easily customized, had decent armour, and an alright gun. The biggest thing was its reliability.
For the most important tank, hands down the t-34. I love the Tiger but it was to unreliable with small numbers built. It had great armour thickness and a powerful cannon but the cons out weight the pros. The Sherman was a great all around tank with a lot of influence in the war. It also had a lot of countries use it. However, the Eastern front was vastly more important than the western front. Thus, the T-34 is the most important. It took the brunt of the German force. The tank would get destroyed but two more would take its place. It was also well rounded tank with fantastically sloped armour. The t-34 was also how you stopped the Blitzkrieg. Quantity was needed more than quality. There is a video of Hitler talking in which he expresses his concern over the fact that in 1942, Germany had destroyed roughly 35000 tanks. That is why the T-34 is by far the most important tank of WW2.
If the Americans used the T-34 line and the Russians used the Sherman line, I would say the Sherman was more important.