What kind of dog would be a good dog for my 16 year old daughter?

My daughter wants a dog that belongs to just her. We have a 2 year old male Shih tzu he is so sweet and he loves other dogs so it would be good for him as well. I think we should get a female since we have a boy already but it's not for breeding he's already been neutered as the next dog will be at the age of 6 months old. I would like breed specific info I already know about shelters. I will end up adopting or buying from a breeder. Thank you in advance for any suggestions. I really appreciate your time and have a good day.