I don't like Chow, Akita, Rottweiler and most German Shepherd/Malanois either. But the dog that always kept me and everybody else who'd been to that house in the car was a Collie. Sneaky mean she was. When the owner was outside, fine. But do not get out and go knock on the door.
My stepson got a bad bite when he was young from a Shepherd. The owners were given the choice of put the dog down or face a lawsuit. They were smart enough to disappear the dog.
My wife got knocked down off her bike by a big chow a few years ago. I had to take care of that one myself as the owners were stubborn.
Somebody dumped a catahoula/lab mix here about a year ago. He put me back in my truck.
Once. My patience level for aggression in any dog is very low.
All that said, I love dogs, there are seven living here now. They don't run loose and the biggest threat to the UPS guy is keeping the heeler from getting in the truck to go for a ride.