We have the larger breeds - rouens, pekins and crested ducks, and have always found them to be very mellow, friendly, and just plain fun. I like India Runner ducks most of all. They are a tall slim duck - some people call them a bowling pin with legs. I think the key is to get them young and spend as much time with them as you can, so they will be tame. Be sure to feed them starter food at first and keep their water as clean as you can.
Runners are kind of unusual too so they can be a great source of fun.
I want to know about those Rouens. I know I would spend a lot of time with them when they are ducklings. Mom says I have to start digging the pond. I will look up Pekins and Rouens and Indian Runners at feather site. I saw some indian runner ducklings at the feed store.