BS! Mastiffs and corsos are gentle giants and not deserving of this level of hyperbole. I've owned both mastiffs and cane corsos, and I've not had a single one act aggressive to another person or animal without presenting a threat. EVERY dog is going to be territorial and protect their home turf. My 15 year old half-blind, deaf, mini-dachshund will nip at your pant legs if she doesn't know your smell, and my 5 year old border collie will howl at anyone who comes knocking at the door. It's what they do.
Pits are a breed that, while maligned, have been interbred into what the public now perceives. They used to be gentle dogs used to protect house and human but are now considered, by and large, mentally unstable due to poor breeding habits and a pop culture desire for "fighting dogs." Mastiffs are still, in general, a loyal, stable breed capable of great affection and act as exceptional home protectors.
Pit Bulls were bred as dogs to fight other animals.
Cane Corsos were bread as Roman war dogs.
Bullmastiffs were bread to catch and hold humans.
Bullmastiffs and Cane Corsos are both twice the size of Pit Bulls.
I think that make Pit Bulls look tame by comparison.
All three breeds need special care in socialization.
Cane Corsos and Bullmastiffs have a reputation of being particularly protective and suspicious of strangers, do they not?