It depends a lot on the point in the game, and which country.
I guess if I had to pik one place that I’d rather have a stack in than an enemy having a stack in, it might be West Russia.
A stack of Infantry in West Russia just gives a whole lot of opportunity. I’m pretty certain that it borders the most territories (7!). Tanks can possibly move into a whopping 14 terrorities.
Most hate to lose
USA - Western US
UK - India
Germany - Western Europe
Russia - Caucus
Japan - Kwangtung (If only because if I lose it I feel like I’m really in trouble) or East Indies (4 points is a lot, and it’s a two turn job, rather than Borneo being just one)
Most want to gain (realistically/relatively short term)
USA - Western Europe
UK - Norway
Germany - Caucus
Russia - West Russia
Japan - India
These territories are ones that make me feel like I’m in business. West Russia less than the other ones, because that’s a first turn given.
Seazones 5, 7, 12, and 60 are major.