Using CentOS or Ubuntu is your choice. Wordpress will work fine on both. CentOS and Ubuntu has difference commands and service names. for example, yum is used in centos and apt-get is used in Ubuntu to install software. Also, httpd is apache service in CentOS and apache2 is apache service in Ubuntu. If you are familiar with CentOS, please go with CentOS and it would be easy for you to manage everything.
I'm a Centos person myself so I'd use Centos 7 but I do use Ubuntu for certain things like OpenVPN, but as stated about it's down to your own personal taste as Debian is what Ubuntu is based on, Centos is based on Redhat.
Ubuntu is good with some specific configurations but if you think overall, then CentOS is perfect. And working with CentOS is easier because of plenty of resources. So I would like to recommend to use CentOS.