The linux variant for the more experienced user I believe should be Debian linux. This variant allows the user to customize the operating system to be more flexible. There are many packages available for this operating system that allow a more individual feel.
Debian has KDE and Gnome available, but the interface I prefer is Black Box. The Black Box interface is smaller and cleaner than either of the others, but allows for additions that make it very useful.
Upgrading the kernel in Debian linux is fairly easy for the experienced user and makes possible the addition of extra packages to perform various tasks.
Debian linux includes a version of Open Office that is useful if not fully complete.
I have used Debian for three years and have had few real problems once I became familiar with the installation package.
This is not the operating system for the beginner, but works well for the experienced user.