Only one answer to this question that I know of.
I have used a Faulks wood duck call for the past 33 years. It is the only call I know that reproduces the soft wee-ee-e-e-ep of the relaxed but active bird. The others I have heard sound like a woodie, but only reproduce their panic call - and why would you want to do that? It is a bit hard to learn, but worth doing.
Many years I don't use it, but this year I called in a flight of three that buzzed our mallard spread and kept going - they turned right around and pitched into us when I blew it. I also called in a very wary late season drake quietly circling our mallard spread on a large beaver pond. Neither time did we have any woodduck decoys out.
It is only available by calling Faulks directly.