I would have to say the BIGGEST BRUTE is the A-10 Warthog. What makes it a brute is that the A-10 is a pit fighter - it likes to get down and dirty in the mud - it can definitely dish out a lot of punishment with that GAU-7 Avenger gun, this is its "Iron Fist", and at the same time, take a lot of punishment.
Whereas, the A-10's high-flying, fast moving cousins are afraid to get into the mud and fight.
Mind you, any high speed fighter trying to take on an A-10 head-on, would have to deal with the Avenger gun firing DU rounds at them. So, the award has to go to the A-10 Thunderbolt II - the Warthog, the Tankbuster !!!