Also remember, in regards to logistics, NCR wins by a mile. Although not in massive numbers like the Enclave or BoS, the NCR military is still heavily mechanized. That means self-propelled guns, trucks to keep up with said guns, heavy weapons like mini guns, rocket/missile launchers and grenade launchers, you name it. The NCR also can use said transport to rapid deploy their heavy, power armored infantry, into numerous hotspots while the Legion still relies on horse and cart. Comparing the NCR and Legion is like comparing the German, panzer led blitzkrieg, against charging, horse mounted cavalry.