Food intake, summer, then winter.
Moscow: 35, -13
Leningrad: 5, -4
Stalingrad: 21, -7
Sevastpol: 12, 0
Vorenezh: 11, 1 (note, also a threatened city)
Sverlodvsk: 23, 0.
Summer lasts from May-November. 7 months.
Winter December-April: 5 months
Moscow: We do not have to worry about starving, as summer more than makes up for winter losses. Moscow is also using every square, with a lot of excess workers either as tax collectors or entertainers (maybe a few more should go from entertainer to tax colelctor). Assuming we don't really need any more of these people, the place is safe to sell.
Leningrad: Not using all squares, and has a very small net surplus per turn. Has a decent amount in storage, 1/5th of the way until next growth. The city is growing very slowly, so there does not seem to be much benefit to the sewers. It won't starve so long as the net surplus is maintained. However, does the front commander (I believe it's Henrik) change it's collection often?
Stalingrad: Not using every square, but any additional square only brings in food, no industry or trade. Thus, we gain nothing except a larger population to possibly make entertainers or tax collectors, and indeed, these fields lie fallow on purpose. (note, some of these existing entertainers can easily be changed to tax collectors, no unhappy people in city). Unless we want more entertainers, scientists, or tax men, we can easily sell here.
Sevastpol: Food surplus, unusued squares, and has two entertainers. Ocean squares can still be tilled to give trade and industry, and I don't really know why those entertainers are there. One can be changed before getting, changing two gets unhappiness. Even if both are changed, still empty ocean squares, and we can always reconvert the minefield as well. We may wish to keep this one.
Vorenezh: Food surplus summer and winter, (indeed, whomever is controlling recources there should take advantage of the suburbs). Can grow fairly quickly. On the other hand, it won't approach size 12 for a while, and the city is threatened by the Germans. I say sell it, and we can reconsider rebuilding it later a few years later if we wish to when the city starts approaching 12.
Sverdlosk: Food surplus in summer, no loss in winter. Growing much faster than Voreneh, and is being transformed into much more of an industrial city by the armaments minister. However, the city has probably still a while until it reaches size 12, and it can quickly rebuild a sewer system if need be. However, it is growing faster than Voreneh, and unthreatened. I would like to see input from the new armamaments minister Greeny on this.
Initial recommendations: Sell Moscow, Leningrad, Stalingrad, Vorenezeh.
Keep Sevastpol, and possibly keep Sverdlosk.
I await further input from my comrades before forming the final verdict.
Edit: In regard to these commendations of selling in 4 cities and keeping the other two, I would ask if the Marshall, using his godlike powers (though he is not god, since we have happy atheism here) could add the option of selling in Moscow, Leningrad, Stalignrad, and Voreneh only as an option to the poll.