Ducks, like any other animal, will taste differently depending on what they eat. Just like one beef steer feed corn will taste different from a free range steer raised on grasses. Grain fed domestic ducks tend to be the best table fare. Of those, pekins are the breed chosen for meat production based on rapid growth, and good flavor when harvested at less than full adult stages. In wild ducks the best eating in my opinion is Wood Duck. This is because their diet of almost entirely acorns gives the meat an outstanding flavor. Next choice in wild duck would be mallard but the flavor can be off if the ducks have been eating a good deal of aquatic stuff instead of grains. When ducks eat primarily aquatic plants the meat takes on a flavor much like beef liver and I'm not a fan of liver. My meat ducks are all pekins raised on grains only and harvested young. They are also heavy layers so you get the benefit of lots of eggs both for consumption and keeping the flock going. Hope this helps.
Very helpful, though now I need to figure out some grains to grow for 'em (and how to get them to eat that and not the water hyacinths or too much duckweed).