It is amazing the extent that dog owners are willing to practice self deception. "It's not the breed, it's the owner." being one of the favorite lies they actually believe. It's funny how you can visually see that dogs can be bred for any number of physical characteristics, but the dog lovers refuse to believe that agressivness is a breed characteristic.
dog bite fatalities '79 - '98
I'm not going to pretend that I don't expect my dogs to protect my family and property. I have always owned German Shepherds first for companionship and second for protection. Although I've never owned an aggressive Shepherd, they've all been protective to varying degrees. I always felt I could leave any of them alone with one of my kids or grandkids for as long as I'd ever leave any of the kids at an early age alone. Some had remarkable babysitting qualities (and I could tell you stories) but I'd never leave a small child alone for any extended period of time anyway.
I don't know enough about pit bulls - I'm sure there are lots of aggessive ones. Afterall, they've been bred to fight. However, I don't think they're all bad and in the hands of a responsible owner, I'm sure they're just fine.
I've owned Labs, Mutts, and German Shepherds. The only dog that's made your list is the German Shepherd. Other than two of the mutts, the only dogs I've ever trusted alone with an infant or toddler has been the German Shepherds. Every single one of them.
The particularly protective Shepherds I would never leave alone with a child or grandchild who was playing with a non-family member. That could be dangerous.