What's best for you depends on where you are.... if you are in an area of extreme winter cold, I would stay away from Dorkings as they have quite large single combs and are likely to get them frostbitten. If you are in an area where it rains and rains and rains and you do not have lots of shelter for the chickens, you might stay away from Houdans as they can get pretty soggy in the crest and even if their health is unaffected, they look pretty unhappy.
As long as it's not wet snow, Houdans that I have had have seemed to do great in the cold. The crest feathers function almost like a parka as long as they are kept dry.
If you are looking for a big, meaty dual breed, I'm not sure if either one is going to be quite right, as over time the meat qualities of some of these rare breeds has been allowed to decline from what it once was. That said, the eating qualities of Houdan and Dorking are supposed to be very similar. Thin white skin, long blocky torso, delicate texture.
Dorkings have a repututation for all going broody - bam! like that! - in late spring or early summer. They are supposed to be very determined.
Houdans on the other hand, are non setters and very rarely go broody.
OK, so there are a few factors for you to consider.
If you do go with Houdan, may I respectfully suggest Cackle Hatchery of Missouri, because IMHO theirs are much better and closer to breed type than McMurray, Privett, or Welp...
Cackle is a small family operation and maintain their own longstanding Houdan flock... they are the kind of hatchery I feel good about supporting.