I've tried Fedora, SuSE, Red Hat, Ubuntu and Kubuntu and I must say Kubuntu (Hoary) is the best by far. You just gotta love the nice apt-get software updating system which downloads and installs any software and usually ported exclusively to Ubuntu, which ensures compatibility.
Additionally you can choose between Gnome environment (download
Ubuntu) and KDE environment (download
Kubuntu). But KDE has proved to be more consistent with most software and has better internationalization and design.
You just gotta get used to the not-root default user, because you can't create any root user, that completely protects sensible system data from any attack (if they don't have the password). You are prompted to type in the root password to perform advanced actions like installing software and so on.