the Dobermantalk forums are fantastic - very knowledgeable people passionate about the breed and love new members and will be great to steer you in the right direction of a reputable breeder.
The Doberman Pinscher Club of America also has a breeder referral list.
Things to look out for: health tested - heart is holtered annually, hips, elbows, VonWillebrand Status is listed etc. - Parents have done something other than being ‘family pets.’
Also a good breeder will crop and dock their puppies prior to sending them to their new owners.
Things to watch out for: Superior-Sized, King, Warlock, white/albino dobermans, touting fawns or blues as rare or exotic. Also Euro/European is often a red flag because lots of backyard breeders/greeders like to pretend that Euros are THE REAL Doberman and sell them as ‘better’ than American Doberman lines - true to type, vision of the breed, healthier (not true) etc.
You’ve already been given names of some good breeders 
Good luck!
A reputable breeder is never a bad choice.
A rescue is never a bad choice.
The only bad choice is giving money to an unethical breeder.
Also (may not be applicable since it seems your in CA) stay away from House of Hoytt or Kimbertal. They are known Doberman puppy-millers and greeders.
(Dobermans are my dream dog and I’m years off from being in a time or place where I can have one so I’m just having tons of fun reading and researching and learning about them).