Why "not the best"? Functionally, each of the classes
fully cover the case you show on your picture. I don't know what do you call "professional design", but at least they look "professional" than your picture.
Anyway, if you still want to show the tree in diagram style as on that picture (why though? all special views can only be justified if they carry some special functionality; do you have such functionality?), I would advise to use WPF. Please see my past answers for general ideas:
Connect different controls
Vector graphics software like CorelDraw or Inkscape in C# or VB.NET