Drupal scales well and is very extensible with features that allow complicated permissions systems, etc. I have built some complicated courseware with it, and big document archives, etc. It has a skilled developer community. I wouldn’t use it for small inexpensive sites, but it’s top tier and free/liberated.

Joomla’s code a decade ago was so inefficient and clunky to work with I could never recommend it, my main interaction with it was troubleshooting and helping folks escape it. Maybe it’s improved.