KDE has been my desktop for a while now. I have a pretty powerful machine and I absolutely love it. I just bought a Dell Ultrasharp monitor and the combo is perfect for me.
I do a lot of video/ 3d and my files are on the net and locally across a bunch of drives and the Dolphin file manager is all I could ask for. It provides all the info and services I could want at a glance and stays out of my way.