I had mules a few years ago. Super sweet loafers. Scovies were nice too, I keep meaning to get some more eventually...There are many different mallard based breeds, they are very diverse. Most require a regular pool of water. Muscovy are a bit different. They can breed with mallard based breeds but the offspring are sterile and called mules.
Muscovy are more mobile on ground, they roost like chickens, don't need to spend so much time in the water, and in my opinion are wonderful pest controls. Mine wander the yard at night foraging. They can fly somewhat, and will breed and brood easily. They don't quack like regular ducks and are quieter, they have a hissing speech.
I personally only keep muscovy currently.
Here's my mule duckie, Starburst.