Assault Class armors make good front-line troops as they can carry any weapon or pack except for the Laser Rifle or Fusion Motar. So you can load up one of these armors with a missile launcher and set out on a full frontal assault on the enemy base if you wish. The hulking brutes of the armor classes is the Juggernaut. These walking tanks cannot carry a laser rifle, but their defense is so high they can take a sniper shot to the head and still have enough life to go toe to toe with a chaingun. They also cannot carry a vehicle, so if you want to get these guys from one place to another, it's best to hitch a ride.
Juggernauts can be useful for anti-aircraft operations, as well as base defense.
Taking one or two along for a frontal base assault is also a good idea as they are the only class that can carry a Fusion Motar.