OpenSUSE - 9/10
As we mentioned at the beginning of this Roundup, the reason why there's no singlepage review of a single distribution is because they're all just so close. KDE is pretty much KDE whichever distribution you choose, and most users will make the desktop their own within weeks anyway.
You could install any of the distributions we've looked at and get productive with your usual array of applications within an hour. What we were particularly interested in was the distro's commitment to KDE and some illustration of understanding what KDE users want.
Kubuntu gets very close. Its team do a very good job of building a great package with superb flexibility and stability, and thanks to the wonders of the PPA, Kubuntu is the best choice for KDE users who are prepared to make their own adjustments and upgrade the official packages with each major release. It also comes with all the advantages of the default Ubuntu installation.
But our winner is OpenSUSE. It's a distribution that's got the professional sheen and gloss that only Novell can bring, and it's a distribution that always manages to bundle a cutting-edge KDE installation that will last you the full nine months of the distribution cycle.
The custom artwork looks great, and shows that the packaging team have a great understanding of what KDE is capable of and what users need from their desktop. Yast is always going to be unwieldy, but its fantastic integration into the KDE desktop (it's written in Qt) makes Linux feel much closer to its Windows and OS X competitors than other KDE distributions.
I am KDE, hear me roar
What this really comes down to is a distribution that is willing to pin its hopes on KDE, and in the current desktop climate, that's becoming an increasingly rare thing.
The KDE development team may seem to be increasingly aloof and separate from the world of distributions (for example, when will they remove the ridiculous blue glow that seems to accompany every window on the KDE desktop, and use a normal drop shadow instead?), but this selection that we've covered shows that there are still plenty of people willing to chase the ideal. Which means there's never been a better time to be a KDE user.