Leningrad
A lot of what-if's have been done on this scenario. Best case scenario for the Axis:The Germans would have been left in pretty good shape if they had taken Leningrad without a costly urban assault. -This would have required that the Finns helped surround Leningrad and participate in the seige..the Germans were just stretched way too thin all along the front. -They also needed to land their forces much closer to the city (than in our OTL). -Also, you'd need more forces to take the area..that would result in a pretty substantial divergence from OTL. -After taking Leningrad, the Germans would need to straighten their lines and prepare for the Russian winter (particularly brutal that year). I believe Blairwitch did a TL with this scenario (Operation Northern Fire)- an excellent story by the way.Had the Axis taken Leningrad early, had Finnish participation, and then straightened their battle lines (not going after Moscow), the Axis is in much better shape the next Spring to cut off Archangelsk, Murmansk and then Blitzkrieg their way East.Just my 2 cents worth