Github pages requires you to have knowledge of several different programs and coding languages like CSS and HTML on top of needing to learn how to navigate the GitHub terminal on your device. You also need a service that can run HTML and CSS. This can be challenging for some because it can seem like there's a lot to learn regarding everything. This isn't necessarily the case however because there are extensive and in depth tutorials and websites dedicated to the learning of CSS and HTML. For instance, in my class we were told to use w3schools for help on both HTML and CSS. The most significant challenges for a new user are learning the coding languages and GitHub. As such, HTML, CSS, and GitHub are all the most significant tools that you will need to learn to be able to properly make a website on GitHub pages.
WordPress through Penn State Behrend is a blog posting service that offers a wide variety of themes and menus that allows you to make a professional looking website with little to no actual coding experience. The most challenging aspect of using WordPress is the navigation through the menus and finding the right premade theme that will fit what you are trying to do. A very important skill in my opinion is patience. That is because the service is extremely frustrating to try to use. There are few themes that actually allow you to edit and change how things will be arranged.
I much prefer GitHub Pages over WordPress. That is because I really enjoy writing out everything myself and using CSS to make my website look more to how I like. WordPress has too many themes and all the menus hardly make any sense. It all feels so convoluted to me while using HTML is so simple and straightforward in comparison. While it may take longer to learn HTML, CSS, and GitHub Pages, it is more worth it in the long run to properly make a website with my own knowledge and skills.
Link to Wordpress.