well, I think that you need to figure out what you want first. Swift Run/Tammy and Cambria/The Whites are about as different as you can get in dobes - decide what you truly want, what you are looking for, what you are willing to pay, what your reasonable expectations about training/ability to train/desire to compete/train are, how well the dog will fit in with your other dogs, and again - what is most important to you - and then look for breeders that match that.
Just in the three breeders you mentioned, they have vastly different prices, health testing, titles and interests as well as ethics.
You can take a nice doberman from good lines and do lots of performance sports and do well, but you cannot take a high drive doberman and make it a couch potato or expect it to be happy just lounging around the house 24 hours a day 7 days a week, for instance.
Just in the three breeders you mentioned, they have vastly different prices, health testing, titles and interests as well as ethics.
You can take a nice doberman from good lines and do lots of performance sports and do well, but you cannot take a high drive doberman and make it a couch potato or expect it to be happy just lounging around the house 24 hours a day 7 days a week, for instance.