I use WordPress for most of my websites and blogs.
There are many reasons why I use WordPress, here are some key reasons:
It's versatility - I can use it to create all kinds of different sites.
It's easy to use, update, change, etc.
Lots and lots of available theme's and plugins to help me do what I want with a site without having to do much coding.
It's updated and improved very often.
There is tons of information around the web about it to help with any need.
There are many reasons I use WordPress for most of my sites, these are a few of the major reasons.