Pretend we have an Super Bowl of military forces. USA, Russia, and China are not participating. The goal is to win a battle, using whatever forces you have available, except nukes and chemical weapons. No allies, no supplies from other countries, just bring what you have.
Cordon off a big empty area of, say, Siberia. Choose a nice summer day and have varied terrain, like hills, airfields, and navigable rivers (in case the navies want to play, too). Assume everything is equal with terrain: mountains, forests, empty cities are divided equally.
Let them go at it. Who would be the top seeds? Who would win?