You will find a lot of post regarding the comparison between Joomla & wordpress. Both are open source CMS having a lots of features. Which one is best is based on your need if you need a blog then wordpress is definitely the best solution for you. If you need ecommerce based solutions then you might think of using joomla for that. There are hundreds of joomla extensions available which extend the joomla functionality & it has a very large community of users. In my opinion if you want to small company website then go for wordpress otherwise joomla is what you are looking for.