I know, we have all heard the tales of Dobermans "turning" on their owners BUT ...hear me out. I have owned 2 Dobermans and they proved to be the most loving, loyal dogs I could ever hope for. Not only are they gentle and protective of you and your family, they are very intelligent.
Even if you live in a small apartment, they will do well. Unlike Shepards, they do not require lots of room to be happy. Of course, you will need an outdoor place to take them a few times a day to do their business but Dobermans are content to be wherever you are. Dobermans are eager to please. You DO NOT have to train a Doberman to protect you, if you treat them well they will do it instinctively.
Now, about them turning on their owners. MOST dogs, including Dobermans will only turn on their owners IF they are abusive.....period. Theres always the rare case of a physical or psychological problem that could cause this but all in all, a Doberman is no more likely to harm his owner than any other dog. My husband is away a lot and I feel safe with my Doberman beside me at night....yes, she sleeps with me. :)