Which beer is the best
Depends mostly on the purpose of the box, but:
Red Hat (Fedora, Enterprise Linux) is easy (all relative

)
Gentoo is flexible
Slackware is die hard
For productions purposes, we mostly use CentOS (R-H Enterprise) and FreeBSD. Desktop, I dunno

. I have never seen a KDE desktop on my desk. Just use windows, as it is most compatible with applications.
So, you will just have to try I'm afraid. Keep us posted.