We have used Landmark some in the past with good results. We got all bull calves so far, so I can't comment on his daughters, though I have been told that they make good daughters. We still have a straw or two in the tank that I'll likely use this year. Landmark is hetero polled and hetero black which likely limited his use in the Gelbvieh breed.
In general, my experience has been that Knoll Crest cattle generally make good females, have performance, and thickness, but may lack a little in eye appeal, though not a big deal for me since I don't show cattle. Another hetero black, hetero polled bull from Knoll Crest that I like is Bennett Ideal. Good daughters, with plenty of milk and performance, though occasionally an Ideal calf may have a bit more attitude than the typical mild-mannered Gelbvieh.
Visa is homo polled and homo black, which likely resulted in more use of this bull. Though I have only seen a handful of Visa cattle, in general I wasn't impressed. They seemed to lack some rib and power, and I've been told that they can be hard-fleshing.