During WWII, the Allies weren't known for their huge tanks. No, the Germans, with their Tiger and Tiger II are what's remembered as the big tanks around. Well, in WWIII, that's no longer the case. The idea of taking lots of fast, light tanks has given way to a new form of thinking. That brings us to the Chieftain, which has the thickest armor and biggest gun in all of NATO's forces. Take a look at it for Team Yankee in this article from Battlefront.
Though its design is initially from the 60s, that doesn't mean that the Chieftain hasn't kept up with changes. The turret has an extra set of "stillbrew" armor. The 120mm gun it sports gives it nearly unmatched punching power. Plus, keeping the ammo separated by charge and round makes the tank more survivable when it is hit by enemy munitions. It carries both armor-piercing rounds as well as anti-infantry rounds (great for hitting bunkers and buildings filled with enemy troops).