I used joomla for like a year, I was really good at it, all sorts of extensions, modules, templates etc.
And the, one day, I was helping my e-pal with his website that was run on Wordpress. After that day, every project I had was run on Wordpress!
Reasons? Well, it is much more user-friendly in my opinion. I am not a 'noob' user, but UI of Wordpress simply amazed me after Joomla. Also tons of plugins, widgets, themes etc.
I would recommend Worpress to anyone!