I think Wordpress is by far the easiest, and the most popular among all CMS. It's flexible too and you can create practically any site using it. My two cents. Have a good day!
I made a small review about concrete 5, you can check it here: http://forums.digitalpoint.com/showthread.php?t=2589280&highlight=concrete5
You choice of CMS depends on exactly what you want to achieve. For a simple blog system, wordpress would be your best options. Thanks
Without giving a second thought I'll go with WordPress. It has taken the best CMS crown from Drupal and Joomla. It's main features are : - WordPress is a Search Engine Friendly CMS with its wide range of SEO tools such as Plugins, Customized Titles, Permalinks, Category and Tags handling and even more. - WordPress can be customized as you want it, because wordpress provides you a huge scope for customization. You can customize settings according to your business needs as following.
It depends on your needs. If this is a simple site, you could probably use Wordpress, which is easy. If you need more, then Drupal is the better choice. You probably don't need Drupal for a simple site because that would be an overkill and would make your life harder than Wordpress.
I have work with use Drupal, Joomla & WordPress also, but found Drupal is the best. Most of the people think that "WordPress is best" but as per my personal experiences & studies Drupal is the best.