I would say that is a matter of opinion to be honest. My parents bought a puppy when I was 3yrs old and sister was a newborn.
Shep (Golden retriever) passed away when he was 18yrs old, we never had any problems with him at all, and my sister and I never hurt him.
When my sister had her two children, she got 2 King Charles puppies, and Mum and Dad had a Dalmatian puppy... again, no problems.
My boy is nearly 3yrs old now, and we have started considering a puppy. We are looking at Labradors and/or Retrievers.
Both are placid dogs and intelligent dogs, so training will not be a problem.