I prefer Joomla as it is a best open system software and powerful content management system used build Effective Websites The Best reason to use Joomla CMS is it doesn't require any technical or web skills to manage any online application or websites.
Vote for wordpress, most popular CMS in the world, easy to use and modification, a lot of plugin developer and theme developer.
My vote also goes to Wordpress, even though I also like to use Joomla. But Wordpress is always more easy to use and it has a lot of power at the same time.