I've tried them all now it seems like. I've installed most Open Source CMS's and other platforms. Some platforms I instantly stop and bail early. Others I stick with. The main ones that I have worked the most with are Drupal, Joomla, WordPress, and sNews. Since I can do everything with Drupal I choose to just do it all with it now. I have my modules I always install also. I'll be putting together a list soon so you can see the ones that I recommend by default when installing. I loved WordPress but found for what I was doing it was much easier to use Drupal with much less effort.
My goal is to try and develop a theme every week. We'll see how that goes. I at least want to be creating one per month to build up my arsenal of themes. Most my themes will be very simple and easy to customize. My focus will not be the graphics as much as they will be the layout, web standards, cross browser compatibility, and speed. I will try and put together some simple documentation the help even a beginner customize their theme and make it unique enough that it won't look like everyone elses. Let me know if you have any feedback for me and suggestions for what you would like to see.