Is WordPress better for a small firm and Joomla better for a large firm?
My preference varies on the requirements and how to address them by researching what is initially available as extensions or modules on each platform prior to making a decision in consideration of time, budget & resources.
WordPress is considered the lighter of the two platforms, and perhaps easier of the two to manage from a user perspective. Joomla is a more comprehensive CMS solution, having been architected/designed from ground up as a CMS (Content Management System).
Pagebuilding solutions alleviate a lot of the front-end design work, and a killer advantage of WordPress is with its pagebuilding tool extensions such as Elementor. Joomla also has pagebuilding tool extensions as JoomShaper’s SP PageBuilder with the Helix Ultimate template system which is also a good tool. If the emphasis of the requirments would be on graphics design, I would opt for WordPress with Elementor.
Joomla has an advantage with multilingual support on a single site implementation, given how menus are assigned to different languages and how articles/pages are assigned to menus.
To be continued...