I have had the pleasure of owning several dobermans over the years. My primary interest with them is in performance and my chosen sport is schutzhund.
During my first few years (2 before I got a working line pup) whilst I researched and learned everything I possibly could about the sport AND the breed - I stumbled across this article. It is, IMHO a decent place to start reading about some good personality traits that you would want in a schutzhund dog. It is on a doberman breeders website as well - and he has some other good info posted as well you can check out if you are interested. Cara Dobermans: Alisa
After working dogs in the sport for 3 years now, I do not feel as thought it is an exhaustive list, but if you are still quite new to the breed and sport, get out there, learn as much as possible about everything. :-) Always listen to what people have to say - You do not have to agree with them, but it is part of the information gathering process.
Go out to clubs and watch regular training, speak with members, go to trials and chat with people. Learning about the sport is so much more then just reading on the internet what people post on forums, blogs, training sites etc. (although those can have usefulness as well, sometimes newbies can be overwhelmed and confused with the oodles of info and sometimes contradictory information).
There are nice working dobes out there, they certainly do not seem to be the "norm". It is far easier to find a dobe that may only be successful in obedience or tracking. Which for me is not enough.
Several of some more well known working dobes have been posted on this thread already - look them up, look at their pedigrees and their titles.
Enjoy the journey, it is not easy, can be exhausting and sometimes you feel like it is overwhelming, but when you have a nice working dog and you are out there training/trialing as a team together - I can honestly tell you, it is 100% worth it!