1946 once a month? Might just as well drop it ...
I do not see a valid solution here. Ya can't keep em all four, ánd have significant numbers. So, you'd have to drop one or two, and if you do so - whichever you pick, you will also drop members with them ...
For me? Cliffs puts the biggest smile on my face, 2nd could still be 1946 - as I can build missions for that one - close behind it DCS. BoX I find mostly frustrating, nearly not as much fun as the others (too complex / too many weird control assignments with the lack of clickable cockpits, it does not feel as nice as the others - or it's maybe because I cannot make sense of the mission editing part?)
I dunno ... I really do not...