Well for security reasons Joomla is pretty shitty, also the way to build themes or templates as they call it is weird and confusing and that without saying that they rarely do an update. Wordpress is easier and faster to develop it may be simpler in a way but powerful as well, and remember Wordpress community is huge and has a lot of updates that does not affect your core wordpress, just security updates, etc at least until a major update is realeased.