I'm attempting to create a standardised page builder using ACF flexible content fields. I'm also trying to standardise a REST API to make it possible for people to create their own frontend editor apps to create/update layout content. The goal is to provide a frontend editor solution once the development of the backend API has stabilised.

The benefit of using ACF is that it is a well-established plugin (really should be core!), uses post meta data, has an out-of-the-box backend UI to manage the content, and is supported by other really good plugins like WPML for translations. There's also potential further benefits of using other plugins related to ACF ecosystem with it.

If you want to view (or contribute!) to the progress of my ACF Page Builder plugin, check it out here: https://github.com/lvl99/acf-page-builder

It's under frequent development at the moment so I'd probably wait until a v1.0.0 release when the API has finally stabilised before doing anything in production with it. I'm really interested in people's comments and feedback on the project.