As for bite force or potential damage, I had a black lab that around my family was great. My son (2 at the time) would crawl all over that dog, take his food, hit him with toys, chew on his ears, etc and that dog wouldn't even open his eyes if sleeping or bat an eye if awake. Yet you let anyone from the outside world into his reach and he would bite and I mean BITE. I had a friend come over and whenever someone was new I would always introduce them a few times till I knew they were okay. Well this friend comes in (6'3 345lbs) and Bob (the lab) grabs him by the arm and drags him towards the kitchen shaking violently.
Not normal behavior from the worlds most popular (family) dog.
IME all the "aggressive" breeds I've encountered have been pretty tame. Sure there were a few that didn't like kids, or cats but for the most part pretty good. The worst I saw was my brothers chow/german shepherd. She was just a straight up mean dog. I would say 99% of the time mean or aggressive dogs are that way because of humans. Whether it be to guard, look like a badass, or to fight. But there are always going to be the odd ball out like my black lab was. Dogs are like people, they have personalities. Not every person is nice and gets along with others.
I have to agree with this. The family of one of my friends had a black lab they got from a breeder. Because the kids were home schooled, they did not get out much and the dog grew up without being properly socialized. Every time a visitor came over he had to be locked up because he would try to attack people, no matter how many times they came to visit.