KDE contributor Alessandro Longo has pleaded the case that Ubuntu should have decided on the KDE desktop rather GNOME. In making his argument, he wrote a blog post with "10 reasons why Ubuntu should use KDE Plasma instead of GNOME."
Among his reasons are that KDE is more "Windows-like", KDE can also provide a "Unity-like" experience, simple by default, Plasma Mobile is still an effort in the KDE camp, KDE has interests in convergence, Qt is multi-platform, KDE Neon innovations, the KDE store, and the Breeze icon theme.
Those curious about Longo's reasoning for believing KDE is better suited than GNOME for the default desktop of Ubuntu can be found via this blog post. But it likely won't shift the needle at all with the Ubuntu developers already sounding firm in their decision to backing GNOME.