if I had to choose between these two platforms, for a beautiful and simple blog I would choose wordpress with the utmost confidence. it's free, it has free themes, it's easy to use.
I have used Joomla in the past but currently, I am not using Joolma. However, I am running multiple wordpress sites. between Joomla and Wordpress, Wordpress is my preference. That's because wordpress is easy to use and can be used to build different sites.
Even though wordpress can be used to build any kinds of websites, wordpress might not be perfect for some kind of website. For instance, a social site built on wordpress or a community built with wordpress looks pretty basic. Wordpress is best for blog, portfolio website, company website, and business website (not an anline store)