I got to know a Rott last winter...contrary to their initial appearance and reputation, THAT'S another dog I'd consider.
Gramps won't let me, but hey. :)
I love Rotties for the gentleness in their nature. Most large dogs have to learn to be mean, but all dogs are territorial, and the Rotty is just a big one. They are loveable and loyal. And not high strung. You could do worse in your selection of dogs.
A brown Dobermann is less nervous than a black one, but both are very loveable and loyal. Even pitt bulls are good-natured dogs. They have a bad reputation because of people who like to exploit them, but if you remember the "Spanky And Our Gang" movies, the dog was a pitt bull...
*did i say too much?*