The hunting rifle is the best common weapon against them. Head shots (in or out of V.A.T.S.) work well, while the Chinese assault rifle and combat shotgun work great up close. The scoped .44 Magnum and sniper rifle are great if you have the ammo. Use grenades and missiles for groups. Be sure to aim low with the missile launcher because it tends to wander a bit in flight. If you have a few seconds of distance between you, drop a few mines for them to run over. The Centaurs are like Super Mutant guard dogs because they are always near Super Mutants. Killing the Centaurs is necessary at times, but they are almost always empty upon searching the corpse. Also, when in a area controlled by Super Mutants, always check the gore bags. It may be gross, but it is a good place to scrounge for items.