Any dog can be a good family dog. If you don't mind my asking, how is your brother handicapped? Personally, I believe the GSD (German Shepherd Dog) to be an ideal dog for your situation.
My own dog is a German Show/American Show cross. These are just lines, he is still a purebred German Shepherd Dog.
GSDs, if trained properly, given the proper care, and bought from a reputable breeder are wonderful.
My own dog has the foundation work to become a Therapy Dog, and contrary to popular belief, this is NOT an easy task. My dog is incredibly sound, and just has an instinct for therapy work. I was at PetCo just the other day, and there was a woman on crutches who had a knee cast on her leg, and a cast on one of her wrists. My dog did not shy away, but rather he went right to her and sat down.
The woman had been admiring Strauss from across the aisle, and Strauss just HAD to say hello. He did not do his normal schtick of leaning against her, because he just knows that that would have been inappropriate for that particular person. He sat quietly and het her pet his head, and she talked to him....it really seemed to make her day
When we are at dog shows, there are many times when people from nursing homes or "institutions" come out with a few residents/patients to see the sights. Many people are interested in Strauss, and Strauss is ALWAYS interested in them. While we do train, Strauss was NOT taught how to interact with these disabled people, he just understands. He takes rough petting all in stride for those who cannot properly control their muscles, he doesn't startle to the loud yells of somebody who cannot control their vocal tones, he rests his head or leans against the frame work of a wheelchair so it is easier for the disabled person to pet him.
If your brother is in a wheelchair or anything of the like, I would NOT recommend a small dog, simply because they could be run over. Most of the time they move...sometimes they don't move fast enough. Dogs like the German Shepherd Dog are large enough that they do not pose a danger to anybody. A proper Shepherd displays courage, loyalty, and trainability. They are used in many facets of human life, from Narcotics dog, to SAR (Search and Rescue). They are therapy dogs, mobility dogs for the disabled, hearing ear and seeing eye dogs. They are just a GREAT all around dog!
While the GSD is a large breed, for what you describe, a medium to large family dog would seem to fit your family better than a small one. Also, the three breeds you want require a fair bit of grooming. The GSD is a "wash and wear" dog. Brush it consistently, give it a bath every now and again, and you've got the perfect pet.
And as others said, there is NO such thing as a Teacup Poodle. They come in three sizes, Standard, Miniature, and Toy. If you live elsewhere in the world, there is one more size called "Dwarf", but from what I know, they are extremely hard to find.
Some questions to ask yourself before you start looking at dogs:
What is the SPECIFIC temperament you want? Aloof, friendly, quiet, laid back?
What kind of exercise and coat care are you willing to give? Small dogs usually involve the toy group, and they require a lot of groom work usually, but not as much exercise.
How much are you willing to spend on a dog? Dogs prices vary from breed to breed.
Are you looking for a dog that is easily well adjusted, and can acclaimate itself to your brother's handicapp?
What kind of life span are you looking at? The smaller the breed, the longer it lives, and visa versa.
What health issues do you wish to avoid? Every breed has issues, but you need to read up and learn about them in anybreed you look at.
Would you consider rescue? Sometimes rescues DO have pups, purebred or mixed.
Are you looking for a low shedding dog, or one that hardly sheds at all?
Do you want a dog with a soft coat, harsh coat, short coat, or long coat?
Do you want a dog that is biddable and easily trained, or do you like more of a challenge?
Ask yourself all these questions, as it can help narrow your search. And PLEASE keep in mind that ANY dog can be vicious if not properly socialized and trained. It is not the breed that shapes the dog, it is the owner, and every dog, like every human, is an individual