Since I had my 1st taste of Mandriva (formerly known as Madrake/Mandrakesoft) back in the late 90s it is the most easiest distro to mess with. They are actually the pioneeres
As mentioned before, they are the creators of the MCC (Mandriva Control Center) or commonly known as Control Center.
Also, has Easy URPMI which is a website for repositories all over the world. So if one is down or no longer supported you can configure your system without even entering a command line (if you want to).
If you are a MS user, KDE is more similar if you are an Apple user, GNOME seems to be the closest to it.
There are other like Enlightenment, XFCE, and many others. Some are more graphic intensive than others.
The differences on the most common Packaging Systems that are Debian or RPM.
*buntus are Debian based, Mandriva are based on RPM. They all have their pros and cons. Most of the success is from the community.
The desktop environment is what people are more familiar with. Depending how good was integrated the experience variate from distro to distro. If you want to go by Distrowatch, is a source of Linux distros; however, is not "THE Site" for Linux distros. There are more sources.