Muscovy and Pekins are the standards for ducks... although I raise Silver Appleyards which are plenty meaty. The key to raising ducks is to process at the right age to make plucking easier.
Most people raise Embdens for meat geese, as I do. But, I also use Pilgrims and Roman Tufted, since that gives my customers a wider variation in sizes for the processed geese.
Also, people who are buying ducks and geese directly from me on a farm could care less about fat content. Actually, they're usually wanting as fat as animals as possible so they can render it for confits. So, recognize your niche and exploit it. Never try to replicate what people can find in grocery stores.
Fat is really misunderstood. Even with the society become "fat concious", obesity and cholesterol levels have still risen. It's not the fat that's the problem, but the fact the fat comes from grain fed animals rather than grass.