I'm sorry I cannot help you with any knowledge of these breeders. Hopefully someone else can chime in that might know.
Have you checked with the DPCA breeders list - it's a start, but you still have to do your homework there, too.
Where do you live? Do you want to buy from someone within driving distance or a further area?
Not that I don't regularly encourage Canadians to check out American breeders, but since both these kennels are located in Canada, I'm going to Assume OP is Canadian and probably would prefer looking at DPCC breeders first
I am unsure if the DPCC's breeder listing is up to date.
Although both names are familiar to me it is only in passing, and neither negative or positive.
However, a quick google search brings me to Cresswell's facebook page. Okay, they show their dogs in CKC and UKC, good start.
Then I look for the Cresswell kennel name in the Orthopaedic Foundation for Animals database. Great sign a lot of their dogs show up including ones they currently own (according to their facebook page). Not so great? Most of their dogs only have results showing for Hips. A couple have results for thyroid as well. That's not a good sign as it is not nearly sufficient enough health testing for breeding dobermans.
Now, I wouldn't necessarily write them off right away. It is possible they do the OFA auscultation and the echo and then just don't send the results in to OFA, in which case they will still have in their possession the evaluation sheet, which would bear the OFA logo on it. It is also possible they only have had their dogs holtered, in which case OFA doesn't accept just the holter results alone. But they should be able to provide a PDF copy of the document or a screencap (although there too I'd be leery because apparently people have been stealing other dog's holter results and photoshopping their name into it.)
I'd also like to see some kind of proof about their vWD status.
No idea about the temperament of these dogs obviously having never met them. I would think they are probably decent as several of the dogs have rally, obedience and various temperament, sociability and obedience test titles.
The major concern for me is the health testing, and if I were interested in one of their dogs I would be adamant about asking whether the heart was tested on both parents of the prospective litter and most importantly I'd ask WHAT was done and I'd ask to see PROOF.
Ultrasound. Their website says dedicated to a healthy legacy & Great temperament. They also seem to show extensively, however their website is incomplete, and their facebook page doesn't list the registered names of their dogs except for one, Ultrasound Titanium. There is a certifiate on their FB page celebrating their 40th anniversary they received from the mayor of Owen Sound, Ontario so they've been around a while. Ok no big deal, let's check OFA.
... they have TWO dogs show up in the OFA database with the youngest one being born in 2012 and the oldest in 1985. Their last litter announced on the facebook page is from November 2018, so possibly from that 2012 bitch. She has Eyes, Patellas, Hips, Elbows and Dentition done which is great but no mention of vWD, Thyroid and most importantly, heart. I find it concerning that a kennel established for 40 years only has two dogs show up in the OFA database.
Like Cresswell I would ask them what they are actively doing to promote a healthy legacy, I'd ask what health tests they do, and I would demand to see proof, particularly of the cardiac. Owen Sound is a 2 hour drive from Guelph, no reason they couldn't have participated in the DCM study that the University of Guelph had on for a very long time.
No way to verify their claims about temperament as they don't have their titles listed on their FB or their website (but that's not to say they don't have any, since like I said it just seems that their website appears incomplete).