I don't know how you can say this when possibly half the climbers use them. They are essentially the same as ABC Huevos/Smileys, except that they are a bit sharper on the corners.
I don't like the Wildcountry because they don't have a transverse taper on the wide axis, which I find to be so useful in placements involving shallow, flared cracks. They are probably the only stopper that does not have this taper.
I do love the DMM and have not found them to get stuck any easier than the Smileys. They do place better in certain situations. The large DMMs, especially, are a lot lighter than similar sized nuts of other brands.