Without a doubt, the Herter's geese float the best (ride the waves most realistically), but their heads are waiting to get shot off and the stem breaks. If you plan on hauling them around a lot and banging them up, go with plastic. If you don't mind repairing dekes every other year and want something that handles the water like cork...go with Herter's.
My two cents: I went with Herter's for years, but now the G&H's are what I take out because they are lighter and I don't feel bad banging them around! As for ducks, I put out my Herter's burlap covered cans whenever I am diver hunting. Heavy, but great in the water.