And heavies are the best class in the game, bar none. Double shooting, AOE, Suppression CC, and guaranteed damage with Danger Zone--their flexibility is unmatched and useful at all levels. I would consider fielding an all-Heavy team if I had the troops.
Sniper is the best class in the game. Squad sight, in the zone, and near 100% shots every time.
My vote goes for Assault class. Run&Gun, lightning reflexes, rapid fire, extra health, and crit machines.
Poor Supports.