Pound for pound, convict and CA's in general. But he did say SA vs African so I'd pick African. Red terrors have some aggression problems as do GT's, but I've seen some Africans that are just plain nuts. Aceii's come to mind, my obliquidens must be kept with my larger cichlids due to the fact that he kept beating SA cichlids his own size from the day he was first placed into the tank.