Well, I had 4 dogs, and then 3, and now I'm down to 2. Even though I miss my other two pups, I really feel 2 is the healthiest number, at least for my household. With more, I feel like the dogs become in tune with each other more, and I'm a part of their pack. I want them to be a part of my pack. They just seemed wilder, and more animal-like in a larger group.
I can understand wanting only one dog, but I feel like a dog needs a little companionship of their own kind. They need to have a member of their family who is the same species as them. Don't get me wrong, I think a dog can be perfectly happy in a one dog home, too.