Anti-air systems have never been important then 2027. From that year onward. wars grew more involved with aircraft. Many countries are dependent on anti-air systems because the enemy has advanced aircraft.
SAMs Surface to air missiles aka SAMs are a great defense, one of the most effective anti-air types it fires heat seeking missile to take down the aircraft that got to close, here are what country and SAM types.
AVSAM (Armor Vehicle Surface to Air Missile)
Country: Russia, China Type of missile: H-44 Cost: 31,076.75 Yuans, 314,430 Rubles = $5000 Time to build: 12 hours per AVSAM.
HSAM (Humanoid Surface to Air Missile)
Country: America, Israel, Type of missile: L-22 Cost, $2,500, 9945.50 New Sheqel, Time to build: 6 hours per HSAM.