i pretty much everytime beeline for flight and radio, when i get the occasion (meaning the game isn't over!).
Fighters are ok, and bombers are great
Think of it this way :
before artillery, you have cannons, able to bombard the cities' defense, then to suicide for collateral damage. They won't do much to the top defender, if it's a high tech troop.
2 options :
1) go to artillery, so your suicidal units will hurt the top defender
2) go for flight, so you fighters can hurt badly the top defender, + recon + bombarding from range + hurting navy + airports (did i forget something?)
I always go for flight, if i'm underdog.
I often go for flight even if i'm the top guy, but when you can have really better/more troops than the enemy, you remember than fighters don't kill units
