AC-130 simply for crowd control. Warthog you can watch it and run from cover to cover or even plant a bomb before it comes back, and when you get the timing down it's easy to destroy. Harrier all you had to do was watch it on the mini-map and make sure you weren't infront of the nose. AC-130 though everyone knows you are watching and waiting for them to step foot outside. You shoulda put dogs in there. I used to use them simply for the force multiplying effect not even for kills. It pretty much doubles the size of your team, they are like that annoying dude running around knifing, but much sneakier and deadlier.