From marching experience in both yamaha and dynasty lines, its hard to say which line is better than the other as they both have their strengths and weaknesses. i will say that the xeno is by far the best marching trumpet available right now. i'm not a mello player so i'll leave that up for mello people to decide but i've heard that the dynasty mellos tend to blare or sound krass in the upper dynamic levels. As far as baritone, the yamaha baris have weak valve action, perhaps do to the guide, but i cant say. I will say that the dynasty baris have far superior valve action however the yamaha baris sound a hundred times better. Dynasty euphs are significantly better than the yamaha euphs just as far as sound quality goes. I would also say that the dynasty contras, while a lot heavier, sound a lot better than the yamahas.
I think kanstul made the best G lines ever made but their Bb's are not nearly as dominant as their g's were. As far as king, they sound pretty good but i think they look kinda awkward, especially the euphs and contras.
What does all this really mean, i'm really not sure, but the only thing that really matters is the player himself.