As someone who spent many years trying to build different ideas on Wordpress/Joomla/Drupal and only getting so far before hitting personal limitations in coding and also spending the last 3+ years using Bubble, I think I know both platforms fairly well to answer this question.
If you only want a CMS, then stick with Wordpress. If you’re looking to build something more complex and are not proficient at writing PHP, JS, or any other language, then that is where Bubble is going to help you succeed.
As far as design goes – that’s an art many do not possess, but to say a Bubble app cannot look good is completely wrong. There are some that are really well designed.
So, with Bubble you’ll be able to create an application much faster, with more complex features (e.g. connect to 3rd party APIs) than you could with Wordpress.