EGGS!
the BEST eggs, WAY better than even my excellent home grown chicken eggs. can't tell you exactly WHY they're better, but every time I eat duck eggs I just think "MAN are those good eggs!"
the perfect food? Duck egg salad. just mayo and coddled duck eggs and a tiny bit of salt. doesn't need anything more. ok, well fresh baked bread for the sandwich is nice, but really it's all about the duck eggs.
many duck breeds are reliable long-season layers, the eggs are generally bigger, with concrete shells that make them keep longer.
aside from that, ducks are beautiful, goofy to watch especially when hunting grasshoppers, don't care if they're not back in the hutch when its raining, entertaining on water and on land, eat bugs, and grow faster than any of the other barnyard birds. and if you have too many drakes, they're tasty.
plus they're great for fine-tuning my border collie's herding skills... ducks are so sensitive to movement and pressure that they really demand precision and skill from a herd dog and their handler.
and did I mention EGGS?
don't get me wrong, I have, and love, chickens, geese, guineas, and turkeys too, but the ducks... well let me tell you about the eggs....