Hi Caroline,
My personal observations are.
We dont find flying off a problem, many of the larger breeds cant fly, and if they know they are going to be fed regularly, they are happy to stay with you. If you do have a problem one, to stop them flying you just trim the wing feathers on one wing, they then become too unbalanced to fly.
We find ducks are like humans, whatever the breed some are mouthy and some are quiet.
Big ducks tend to be more scatty than calls, but the calls are not good layers, and the eggs are small anyway. So probably the best thing is to buy ducklings, and handle them regularly. Make sure they have been properly sexed before buying, you dont want to end up with a load of drakes.
Breeds I like.
Egg production, just rough figures
expect
American Pekin 100 - 130 eggs per year (Pure White Duck)
Aylesbury (mainly a table duck) up to 100 eggs per year (White Duck)
Rouen Duck (mainly a table duck) probably more friendly than other breeds. 60 - 90 eggs per year. (multi coloured very pretty)
Khaki Campbell Duck. (egg laying duck) in my experience a little scatty, 180 - 200 eggs per year (brown head, plummage khaki/reddish.
My favorites are the American Pekin and Rouen, but it is probably just because I particularly like them.
The only other thing to look for is to make sure they are healthy. Look at eyes, should be bright, the duck should normally try to get away from strangers.
Plummage should be clean and smooth. Check feet for any signs of calluses or sores., check the underside of feet.
Check the duck feels plump, but be careful with handling, if they are in lay.
Check the vent, it should be clean
Hope this helps
John