All of my WordPress web designs are created using either bespoke themes that I code from scratch, or a tailored existing WordPress theme.
WordPress is a very secure system. However like with any software, it can be hacked if the software is not kept up to date.
Using a WordPress web design plugin called Yoast SEO, WordPress becomes a very powerful SEO tool. The plugin can be found here. WordPress can be used as a blogging platform or regular CMS for a business website. Either way, WordPress will have you high on the search engine listings.
WordPress design has become very popular because of the ease with which you can download and install a WordPress theme from sites like Theme Forest.
However you will still need expertise to install, configure and tailor WordPress themes, especially if you have no programming skills.
WordPress themes are a quick and inexpensive way of getting a great looking website as long as you do not want to change the look of the web site too much. If you want to make a lot of changes to an existing theme you should ask me to design a bespoke theme for you.