Hi Guys,
I agree, Stalingrad was a huge disaster not only the collapse of the front and the loss of the 6th army, but also because it prevented german access to oil suplies in the east. And it also stopped the german effort to reach the turkish border and force turkey that way to join the axis (in the caucasus as well in the middle east and africa.
I do believe Leningrad was a major defeat, but the consequences were not were important as those of the battle of Stalingrad.