I completely understand. I have one Pekin left, and as much as I love her personality, I will unlikely be getting another. When they get injured, it takes a lot more time to heal them up.
Welshes are a pretty sweet birds. I do love my girls. Any medium weight will likely fit what you are looking for. Buffs, like
@HeatherKellyB mentioned, would fit that too. I mentioned what I could think of at the time. Ancona, are another breed that could work for you.
Muscovy hens do pretty well with other ducks. Drakes are a bit hit and miss like any drake is. Muscovy and other ducks will take a bit of time getting use to one another. They are different species, so they need to work out the kinks in their communication. I found the Muscovy to be very reserved at first and let the other ducks pick on them. After getting comfortable with their new surroundings, they let the other ducks know they should not be messed with. My Muscovy are always the first birds that accept new additions to the flock. With young ducks, the muscovy only have to give them a look get them to respect their boundaries. The Muscovy do occasionally like to stir up trouble, but that is just in their nature.