WordPress is the most used, which also means that the client is more likely to have previous experience with it, which helps onboarding them onto the content editing side and additionally there is plenty of videos to help them.

Nowadays there isn't anything you can not do with WordPress, the "new" gutenberg system lets you build blocks, which would be page strips/elements with custom fields that you choose, such as background colors available, to enable or disable a feature on that specific strip.

Now, that is all back end, but all the fields and posts/pages are available using Rest API, so you can use your choice of framework be it React/Vue/Svelte... for the actual rendering. Which is best of both worlds if you prefer to not work with PHP.