My best hawk killers/fighters in more than 20 years of chicken keeping/breeding have been a RIR X BCM cross, La Flèche, BCM x Araucana cross, BCM and my guineas.
Only yesterday the La Flèche rooster stopped the hawk mid attack and it had a very narrow escape. We stood only about 3 meters away when it happened. This rooster already had several encounters with hawks and furry predators in previous years and lost his once outstanding beauty because of several severe injuries he sustained while protecting his flock.
My guineas once even plucked the hawk right off the protective netting covering the chick run. They literally ripped him apart, I almost felt sorry for the hawk.