Never used Drupal, but a friend of mine just quit Drupal and moved to Joomla and he says it was a very good choice. Good luck.
Someone mentioned the speed issue when a page get busy. I have used e107 on shared account with 15k visits per day and no speed issues at all.The average time to load a page was 1 sec to 0.5 secs(!!!),and thats whithout enabling the cache!
Joomla is great if you have a small page Joomla is great if you have a popular site and dedicated hosting Joomla is not great however, if you have shared hosting and a popular site - the amount of SQL queries can overload the hosting companies SQL server, especially if you use a SEF (search engine friendly) extension or use a Joomla stats engine. Joomla is my choice of CMS but watch the page views and keep your database hits down to a minimum unless you can afford dedicated server hosting - which I cannot!