What to buy?

[CheerfullyInsane]

The usual answer is, buy the one covering the battle that interests you the most.

From the above list, I'd probably pick France'40.
Loads of movement options, early-war so tanks aren't the killer behemoths that they become.
Only drawback is that the Allies have no real options other than being defensive.

Moscow'41 is very good as well, for much the same reasons.
But it is BIG. I mean, really big. Not an issue in and of itself, but it is time-consuming especially playing hot-seat.

Not too fond of Sicily.
Just as well-designed/researched as all the other titles, it's just such a grind due to the terrain.