We worked with Joomla even long before it was Joomla, used to be Mambo. All in all, it is quite a good and robust CMS. Then, when development of Joomla stopped a couple of years back, we switched to WordPress. I personally found Wordpress to be easier and quite modern. In the meantime though, Joomla development continued, but I would say, use WordPress becuase you are sure to achive your goals quickly and safely, and perhaps, just as a hobby, try Joomla for non-missioncritical tests etc. This will give you a better insight of Joomla and for other missions, you'll be in a much better position to choose between the two (and perhaps even other CMS). Good Luck!