@Endeer:
I look at cities form the axis view point. The most economically feasible cities to take are: Paris, Lenin/Stalingrad, Moscow, and Cairo. this giving them 8 including Warsaw, Berlin, and Rome. Troops in Stalingrad will protect from a blitzing devision of tanks to take the city. This would protect the allies from defeat for a turn at the least. And by this I mean bear minimum forces to get the job done (this would be done by calculating threats. So in my opinion I would put ENOUGH troops in Stalingrad, Rest in Moscow, and your mech. Infantry, and tanks in the middle of two cities so they can react to the threats that apply too the cities as they come. Another point is that Moscow will always be a priority over Stalingrad. but you have to realize, if the Axis hold Stalingrad, they can put three tanks a turn within blitzing distance of moscow. Any comments?
3 axis tanks a turn is not good, but not as bad as it sounds too. Stalingrad is a little bit out of the way for Germany, taking it is 1 turn, the next turn it can place 3 tanks, and then the next turn those 3 tanks can come into action. That is 3 turns, a long time in a game like this. In fact, after 3 turns, Moskou might have fallen anyway, so for Russia i can live with that.
Now if Moskou falls, there won’t be any extra units being built and Stalingrad will probably be burned to the ground soon after.
Tanks in the middle of 2 cities is great, but when the Germans have come within reach (and you may expect them to come with too many to counter-attack, especially if they have come from a Rumenian Major IC) those tanks will need to decide where to move to, and most likely this will be Russia. And if there are italian can-openers the way might be opened fast.
A lot depends of course on the situation of the moment.
Edit: for me (talking as Allies) Cairo is the key.