Zaidoo, in a lot of your posts you mention wanting an "intimidating" dog or a dog who is "a bit aggressive". Why do you want an "intimidating" looking dog? Do you live in an area with lots of crime? You can count on almost any dog to bark when a stranger tries to get in the yard. And barking will scare most burglars away, even if the barker is a six pound chihuahua, because it attracts attention.
The danger with a dog who is trained or encouraged to be aggressive is that if he attacks the wrong person (for example, dumb kids climbing over your fence on a dare), several negative things will happen. First, everyone will gasp, "Oh my, [breed] is so VIOLENT!" and give your dog's breed a black eye. Second, you may face a lawsuit. Third, your dog may well be put to sleep; this is especially true if he gets out of your property and attacks someone or if he attacks a hapless deliveryman. It's hard work to properly train a guard dog; given your work hours and lack of previous dog training experience, I wouldn't recommend it.
I've never had a doberman, but obviously from what people say here, they are not a "beginner's" dog. If you DO get one, I too suggest going through a rescue. Not all rescue dogs have "baggage", some were dumped for the same old reasons--"moving away from the city/into an apartment", "he sheds too much", "we are changing the furniture and he doesn't match anymore."
A good rescue will evaluate their dogs and be able to tell you about their personalities and any "issues" they have.
German shepherds are one of the most popular dogs in the US (I think number three in the AKC?) and therefore there are MANY unscrupulous breeders producing poor examples of the breed, riddled with health problems. So screen carefully if you go the breeder route. But personally I would go to a rescue or the Humane Society (plenty of shepherds / shepherd mixes there) and save a life.
You asked in a different post about how to make the dog focus on you more than the rest of his family. He will probably focus on whoever trains and walks him the most. I got my dog when I was thirteen and did all her training myself; even when I had to go away to college and was gone several years, I was still "number one" in her book.