Wordpress meanwhile is the most known content management system of the world.
Many customers like the availability of a lot of plugins installable and feel capable to handle the system.
Because there are thousands of developers active in the wordpress community, you will find a solution for any problem and a tool for anything you are interested in.
A problem is the big database. For multilanguage sites wordpress is a bad choice, too, because wordpress core does not include various languages.
Whether your used plugins fit together with in that case used additional plugins is a possible point of conflict. So if you are planning bigger multilanguge sites, Joomla should be preferred.
We are experienced in handling smaller and complex web projects realized with wordpress.