I would recommend an older dog from a shelter. There are many who are already housetrained and have some house manners. You will know how big it will be. The people at the shelter should know something about the dog, such as it's energy level and anything that needs to be worked on. The dog can wait to go out better than a puppy. With your work schedule, an older, settled dog would be your best choice. And a shelter dog is very grateful.

I don't think you would want a puppy. They are high energy and need a lot of training and time. Even a pure-bred puppy can develop health problems.

I have three mutts and a bunch of cats. I keep the cat food on the dryer and the litter box in a room with a gate.