Trust me on this. Both are the most user-friendly distros of their kind. Installation is simple on both, and you can get right to work with a minimum of screwing with the settings.
Both distros will give you the very best that each desktop environment offers.
Overall, Ubuntu is regarded by many as the best Linux distro out there.
I've never tried Kubuntu, but if it is anything like how Ubuntu has implemented GNOME, then Linux lovers *need* to give Kubuntu a try.
I have, however, tried quite a few KDE-flavoured distros, and PCLinuxOS is second to none. It is not only a dedicated KDE-only distro, it is also updated on almost a bi-weekly basis. PClinuxOS is fairly bleeding-edge, BUT is incredibly stable at the same time.
Hmm, if you consider yourself to be an advanced computer user, you probably won't be happy with PCLinuxOS.
You might want to try arch linux (http://archlinux.org/) (which I use), or Slackware (http://slackware.com/). Ubuntu is good for any skill level, making it an excellent choice to get started with linux.
In terms of KDE vs. GNOME, I use neither but between the two I personally prefer Gnome, it's a lot more streamlined and professional whereas KDE is all bubbly and large. There are other choices, I myself use Openbox (http://icculus.org/openbox/) and both fluxbox (http://fluxbox.sf.net/) and XFCE (http://www.xfce.org/) are excellent choices.
Oh, if you're looking to be a 1337 haXx0r and enjoy watching text scroll by your screen all day, use Gentoo (http://www.gentoo.org/).
i agree ive always used slackware and its very user friendly yet advanced at the same time .. comes with both gnome and kde as selectable interfaces .. also has blackbox /fvwm and others
