Choosing A Breed

My younger foster brother Jack moved in with me recently, he's 18 and I'm 26, and I want to get a dog to keep him company when I have work for can't be home with him for whatever reason. Jack has been through a lot of very serious and traumatizing abuse and gets upset and scared extremely easily, I need a breed of dog that is gentle and calm, preferably one that doesn't bark often because he is frightened by loud noises, and one that is likely to comfort him if he gets upset when I'm not around.
   
I've had people suggest breeds such as Golden Retrievers and Labradors before, I've been leaning towards a Golden, but was wondering what breeds of dog have the best disposition to help my brother. I've heard that dogs can be great therapy for abuse victims, but basically would just really like for him to have some company when I'm not around.
   
I've also had people suggest rescuing Pitbulls and German Shepherds and other similar breeds, and although I know that many of them are wonderful dogs, I can't risk getting a breed that may have a temperament problem, because if something does happen and Jack gets bitten it will set him back very far and likely really terrify him. And it certainly won't help with his trust issues.
   
So just wondering what breeds you would suggest or advise against, thanks for your time.