Which premium is best to buy?

hello, I want to buy one premium because of discounts, but I’m struggling between Mig23ML or Draken. Also I was thinking about buying CV 90105 or premium Leopard 2A4 instead, but I want to buy only one and I completly don’t know which I should pick. I would like to add that I’m mostly struggling between air tech tree Russia and Sweden because I want to grind them but i don’t know which is more worth grinding.