We have English Orpingtons, Silkies, Easter Eggers, Australian Spotted ducks, and Call ducks. The Spots are our favorites and we like ducks more than chickens.
Ducks do more good and less harm to your yard if they free range like ours do. If you want to breed and hatch, thete are no ordinances against drakes while many areas have banned roosters. The duck eggs are more expensive and more "rich" than chicken eggs. Both ducks and chickens are seasonal layers but our chickens lay year round while the ducks take a break from December to February. Duck eggs store easily for 3 months in the fridge so only hatching is effected by the seasons and I like taking a break from hatching and raising ducklings. Since we have bantam ducks we get chicken sized eggs from our 2-pound ducks so there are no conversions to make when baking with duck eggs. The feed to egg ratio is much better because ducks forage more and eat less feed. We keep feed out at all times but we rarely see the ducks near the feeders.
Duck poop is ideal for gardeners because it does not have to be aged like chicken poop. It is easily liquified and turned into instant fertilizer while chicken poop is harder to break down and it is too hot to use straight from the bird. The ducks weed the lawn and mow the grass very nicely without scratching or digging dust bath pits. They love water so if you put their water containers on dirt it can get muddy but if you move it around on the grass it waters your lawn. Our ducks need far less shelter and they love the rain, which is ideal in the Pacific Northwest. They also eat slugs and snails, plus they eat mosquito larvae from standing water. Chickens will eat bugs too but the ducks are more invested in cleaning the yard of pests.
We find ducks to be so much more social and entertaining. They are definately smarter than chickens. They will lay their eggs in a nest on the ground and then move their nest when their eggs keep disappearing while chickens will use the same nest box over and over. Ducks are good mamas but so are some breeds of chickens. The ducklings can be sexed at a much earlier age (before they are 2 weeks old in our case) and they start laying at 4 months old. They live longer than chickens and are reproductive longer.
We have been tempted to get rid of the chickens and just keep the ducks but our chickens and ducks are both grandfathered with code changes being more restrictive so we need to hold onto the birds we worked so hard to keep. We do like having both chickens and ducks but if we had to choose one or the other we would give up the chickens and keep the ducks.