I run Debian "Testing" on my TorrentFlux/Ampache server,
Protech ONE on my Lifebook p7010 (ubuntu derivative for Pen-testers and programmers)
and I run standard UNSLUNG on my NLSU2 (my Printer server).
I'm biased to Debian since I like the deb packet system, for server use, my penny is on the debian testing or stable.
For desktop use I like ubuntu, any ubuntu flavour is good. The upside is that you can get help from all the debian based distros forums. And in this case the Gentoo crowd are some of the best experts on eccentric problems.
I have tried out PClinuxOS for about 6 months and it works OK, it is good at finding hardware, but the kernel in their repos are old, the latest is 2.6.17 and on my Debian I'm running 2.6.24-1. getting the HDA_intel in ALSA to work is a ***** on any system but completely impossible on PCLinuxOS due to the old kernels. Once you start to do somewhat more advanced work with PCLinuxOS it reveals this weakness.
On the strong side they do use apt-get and synaptic to manage the RPM system effectively removing dependence problems. They do give you everything you need to make the average user happy and Tex is quick with updating the repositories.
I do recommend that you check out
www.distrowatch.org
Chris