Hi @Amanda - I evaluated Joomla, Drupal and WordPress over 3 years ago. Joomla had serious issues that caused me to drop it early and never revisit it. It's architecture is complex and rigid, at least it was 3.5 years ago. For example a content item was tied to a menu item; you couldn't easily mix-and-match, and their URL structure is of the 90's era variety that make these easy on the programming but hard on the user and hard on the SEO. And From what I've heard Joomla has not changed much.
3.5 years ago I picked Drupal and worked with it for 2 years. Then I took on a WordPress project with the intent to return to Drupal. By the end of the project I realized that I had zero desire to return to Drupal as it was just painful to work with. Then about 6 months later I got offered a great hourly rate to work on Drupal project only to finish the first phase for the client and tell them they needed to get someone else because I wasn't going to work with Drupal ever again.
I could go in depth, but suffice it to say that you can get 85% done in Drupal in 1/3rd the time it takes with WordPress, but then the last 15% takes 10-25 times as long. With WordPress the first 85% take a bit longer than Drupal but the remaining 15% is usually only about 3x more difficult, not 10x to 25x more.
One of the key things I notice that Drupal has WordPress doesn't is Views and an admin UI for created custom content types. However, after working with WordPress I'd far rather do it the WordPress way than the Drupal way because, while it requires code, WordPress' way is much more straight forward and performant.