The hunting rifle is the best common weapon. Head shots in or out of V.A.T.S. work well; Chinese assault rifle, or combat shotgun up close. The scoped .44 Magnum and sniper rifle are great if you have the ammunition. Use grenades and missiles for groups. 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. They will run over them. The Centaurs are like Super Mutant guard dogs, because if you see one there are probably Super Mutants near. 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..