WordPress is a core Blog platform, and has been extended to a CMS platform.
WP was a blog platform that has been extended to be a full CMS, it is light and can be faster than Joomla, with better SEO.
Well supported, 30% of the market. Works well on LAMP stack.
Trade-off's; aging platform core, WP will have a difficult time with future core improvements and to use newer technology, what makes WP good, is also its weakness. Poor media features. Needs lots of plugins to add features, some that should be core features, like Widget management, media directories/organization, security issues with increased use of plugins.
The roll out of Gutenberg showed the issues with attempting to improve WP core features, and future issues with improvements.
I recommend the use of the best platform that supports the clients needs and requirements.
Both platforms have improved and have some good and bad things about them, they are more similar than different.
I see many clients looking to migrate to WP from Joomla, Wix and Squarespace, also see requests WP to Wix and Squarespace migration, but very few to migrate to Joomla.
I also see more request on security issues with WP due to lack of updating, old PHP, and bad plugins, this is also since it is increasing in use over 30% of projects. Like any platforms it has to be done with correct procedures/processes and maintained.