Use Arch Linux quite a while, I like the “pacman” command-line, simple and easy installing packages. Then I think about the other package managers such as deb with aptitude, rpm with yum or zypper or urpmi, how will they look like? Because of this, I tried several LiveCDs/LiveDVDs with VirtualBox: LinuxMint 13, Ubuntu 12.04, Fedora 17, OpenSUSE 12.1, Debian 6.0, CentOS 6.2, PCLinuxOS 2012.02, and Mageia 2.
I didn’t go through all the distribution thoroughly, just tried the installation, a web-browser, and the package manager.
PCLinuxOS and Mageia are using KDE. Both requires quite higher resources especially for the video memory in VirtualBox. For me, both are similar. Only difference is the package manager, PCLinuxOS uses aptitude but with rpm packages. Mageia uses urpmi.
Then Fedora and OpenSUSE, both are using GNOME3. It is also require more video memory, however, if memory not sufficient, it allows using GNOME Fallback. That is why I like Gtk+, but not GNOME3. With 256M memory and 32M video memory, OpenSUSE will fallback, but Fedora will not. For me, both Fedora and OpenSUSE are also similar. The only difference is the package manager, Fedora uses yum and OpenSUSE uses zypper.
Actually, Ubuntu is also similar to Fedora and OpenSUSE, the differences are using Unity instead of GNOME3 and the package manager is aptitude. I said similar to Fedora and OpenSUSE is because of the similarity of Unity and GNOME3. The package manager is totally different because it is debian-based.
I also tried CentOS. I feel comfortable with the desktop environment, because it is using GNOME2. However, I cannot get the GNOME3 with the repositories. So, I cannot use the latest packages.
Next, Debian. For me, it is the worst among what I tried. The reason is because of Iceweasel. If Iceweasel is as latest as Firefox, I might consider it. Yet, the version of Iceweasel is 3.5.16 in Debian 6.
Then, the best is LinuxMint. Because it uses Mate as the desktop environment. In the usability perspective, Mate is more preferable, because I need to open a lot of applications when I do my work.
As a conclusion, for me, LinuxMint > Ubuntu > Fedora OR OpenSUSE > CentOS > Mageia OR PCLinuxOS > Debian. However, the best of the best is Arch Linux that I am using.