The Voxengo GUIs have evolved nicely imho, and so have the GUIs of other plugin vendors. My favorite recent gui development is Fabfilters v3 of its delay plugin, Timeless.
I do wonder what improvements could be made to Voxengo plugins. I can only make suggestions for the plugins I use, but those will usually be from the perspective of a long-time user. A new user might feel very differently about it.
But first I‘m trying out some colours schemes

