we have the light tank and the normal tank, why don't we have a heavy tank to weigh it out?
incase you need an idea:

i'd suggest something similar to the above because the barrel is larger, and there's plating on the sides of the treads.
it would move slower too, obviously.
So, the default tank, but slightly larger, thicker plating, larger cannon, heavier rounds, and general ass-whoop-age.