I don't think Knockouts are popular with gardeners. They seem to be more popular with the general public who don't want to garden at all. They just want something they can toss in a hole and it will grow. A true gardener doesn't mind buying a variety that looks more like a real rose with the extra care it requires.
An alternative Rose that I have been growing is "Easy Does It." It is smaller than Knockout and seems to bloom more. The blooms have more fragrance and they look more like a rose. They also stay free of black spot even better than the Knockouts do here.
