If I could only have two, I'd have to go with my Dutch Hookbill pair for all-around calm, friendliness and pretty blue eggs...
But if egg production was my mail concern, then I'd go with a pair of Campbells...
Or, if I wanted to be entertained and have lots of pretty green eggs, I'd go with a pair of Runners...
Which is why I have all three breeds AND a few spares!
Oh, and with one pair of ducks, your hen won't necessarily be bred to death. In the book
Keeping Ducks and Geese by Chris and Mike Ashton, they state that a pair of Runners is a perfectly adequate arrangement (in fact, I myself have a pair of Runners that get along famously), it's only when you have more drakes than you do hens that it begins to become an issue. I "rescued" my first three ducks (two Khaki Campbells and a Jumbo Pekin) from a flock where they were the only three girls with 7 Campbell drakes -
THAT was
NOT an adequate arrangement. But a single pair
should be fine.