Duck eggs are the best. My family used to keep khaki campbells, muskovies and aylesburys, as well as a few mallards and odd crosses. Huge yolks and firm albumen. My mother's yorkshire puds were excellent - she always claimed it was the eggs that made them.
Love duck eggs. Bizzarely, my local fishmonger sells the best local ones!
Quite often get a double yolker too. My girlfriend thought I was winding her up when I mentioned these.. first one I poached from the carton was a double!