Stafford were one of only two breeds recommended as family dogs (by Kennel club I.think?)
The aggressive dogs are nearly always due to stupid or violent owners. People who don't train or treat their dog correctly, or people who train their dog to be aggressive.
There are banned breeds in this country - because they are breeds prone to aggression. Staffies aren't. I felt the same as you, since getting a dog however, I've realised it really isn't so much breed as owner.
My dog was attacked by an instantly aggressive dog. He ran over to mine and started attacking him - my boy was only 18 WEEKS old. We were in a field which was empty but for the two of us - we weren't in an on lead area. The owner stood there and sneered that his dog didn't like mine because he was still intact. Of course he was, he was a young puppy! His was intact too. The owner didn't apologise or put his dog on the lead. His attitude seemed to be that he supported his dog attacking others. I picked up my dog and left. He seemed more dangerous than his dog.
The owner was a very middle-class, well dressed man in his 60's. The aggressive dog? A very beautiful, biscuit coloured, smallish cocker spaniel.
There are some terrible, dangerous dog owners, more than you'd imagine. There are some reactive and nervous dogs but they are usually due to abuse by humans.