Drupal is recognized as more effective one of the two. However, with discharge of joomla 1.6 newer and more effective features happen to be added like Nested Groups, Granular ACL System, Tableless Core Components etc that have been missing in comparison to drupal formerly. Same with there any reason for using drupal now?
For me Drupal is much better for additional complicated sites...Joomla (and Wordpress) could be extended to operate weight loss complex websites however their great strength is the fact that as they are they are able to provide nearly all functionality that's required for any fundamental website basically Joomla is much more of the 'off-the-shelf' solution while Drupal is much more effective (it's entire makeup is extensible and modular) but requires more configuration along with a slightly steeper learning curve.
Take a look at this article, excellent comparison of Drupal 7 and Joomla 1.6. The road that stays out a lot more than every other in my experience is:
Drupal 7. continues to be more effective framework and even stretches its lead.
Thats a bit the problem. I'd state that Drupal is inferior to Joomla because of its insufficient object orientation, while the majority of the weak points of Joomla could be solved through the large numbers of extensions available.
I'd state that there's not good response to this and also the best answer for you'll be to check both systems and find out which you prefer better.