On a side note: Greyhound are sweethearts!
If you go to a rescue, you'll defiantly fall in love with them.

If you do go doberman, defiantly invest some time in training. It's hard to go against what a dog was bred to do (guarding, for dobbies), and they'll be very protective of anything they consider 'theirs' (people, places, ect). This isn't to say their bad dogs, on the contrary they can be awesome, just make sure it's a reputable breeder that breeds for temperament as well as looks, or if it's a rescue that they have some information on the dog and why it was turned in.