I’m now running two PHP-Nuke based sites and one Drupal site. Both have their good and bad points, so here are my thoughts.
With PHP-Nuke, Francisco Burzi runs the whole show and he usually seems to ignore suggestions. PHP-Nuke is a big, complex package with lots of source files. Modifying Nuke is tricky, but it’s fairly easy to configure and install without any programming.
Drupal is very small and modular. Many developers are involved and the community is very active and open to outside contributions. It’s not as full-featured or stable as Nuke, and it’s a lot more difficult to configure, but it’s a lot more flexible. To really get the most out of it, some programming work is necessary. There are a lot of existing modules to add functionality, and it’s possible to write your own modules.
I probably wouldn’t be able to do a site like ShareYourMusic.com in Nuke, since it doesn’t let you add new object types (such as tunes) and integrate them as thoroughly with the rest of the site’s content. When you add a module to Nuke, it’s pretty much separate from the rest of the site’s functionality. Nuke modules can’t extend other parts of the system or modify the functionality of other modules. Drupal’s object-oriented architecture makes all of that possible.