I would say go by what duck looks most appealing to you. You are the one who have to clean up their mess, so at least get paid back by something that says please forgive me and am I the cutest thing you have ever seen.
Unless you are going only for commercial value, which most of us don't. The egg numbers are given by breed statistics so they are pretty much set. Obviously they are also determined by diet, light exposure and if they are overall happy. Stress, like extreme heat or being stressed out by other animals will reduce their egg laying. Another factor is your pets. A cat is less likely to attack a full grown duck, if it can fly or is so large that the cat backs off. I went for Saxony ducks, because I am German, but also their size works well with my 4 dogs and one cat. I also like their looks.
