To argue that one nation saved the rest during the Second World War is laughable.
Assigning greater value to one at the expense of the other cheapens the efforts of those involved.
In saying that, I would argue that nations like France, Poland and China among others deserve way more credit than they ever get, rather than everyone constantly going on about the 'big three'.
My main gripe with all this is, which is mostly unrelated, is that the Second World War wasn't the second World War. It was at least the third.
France, Poland and China, though they all suffered in WW2, especially Poland and China, which lost 20million, don't deserve more credit than they got. They couldn't do anything. They were occupied. They didn't drive the enemy out, others had to invade to enable their freedom. The Poles were brave, especially in the Warsaw Uprising where the Soviets sat by and saw the Polish Resistance wiped out to make it easier to control after the war.