A fun thread on independent website kubuntuforums.net asking why use Kubuntu rather than the multitude of competition.

Some answers:

(1) I prefer the KDE look
(2) The friendly community

I just like KDE and Kubuntu seams to give the best KDE I have tried

I use it because I like Ubuntu, but but want customization options. Ive tried a lot of other DEs but none is easier to use and more customizable than KDE.

the community rocks

I use Kubuntu because it's Ubuntu, but with the awesomeness of KDE. So the familiar technology, coupled with the superior DE means I have never been happier with Linux on my desktop.

I love its pure, unmitigated, raw POWER! It allows me to do more with fewer keystrokes or mouse clicks than ANY other OS available. Dolphin is just an example.

Kubuntu offers a compassionate community, the excellence of KDE and the breadth of the Ubuntu ecosystem.

Kubuntu has a good and familiar look (for those of us coming from Windows), a good base in Ubuntu, and the ease in which to add software and repositories. I also find it cool that both KDE and (K)Ubuntu have 6-month release cycles, meaning a new version of Kubuntu means a new KDE (though a couple months off).

Lovely.