if you have a toddler it's not a good idea to get any of the 'working' breeds. they are extremely strong and can knock a toddler into a table or something else way too easily.
don't get any dog known for snapping, the most common dog bite comes from a german shepperd. a little kid slapping a dog like that around isn't a good thing.
don't get any herding dog, those will nip at kids while at play to try and herd them.
i'd suggest a Boxer. those are extremely patient (you can pull on their ears, slap them around, pinch their cheeks etc without them growling) and good with kids.
the original pit bull, the stafordshire bull terrier, had almost all tendency to bite humans bred out of them, so if you can get a pure-bred staffordshire bull terrier, those are very good with kids and medium in size and while theyre super mean with other animals, you have to really piss them off to get them to bite a human... they're called the nanny dog in england. not the same as the american pit bull terrier.
my pick for your needs is the Tibetan Terrier. i attached a pic.....