Backdrop is a modern website driver for custom functionality and multiple user-levels. It's an ideal fit for a variety of medium sized organizations. Allsite is a member of the Backdrop-contrib github team and maintains open source addons available for public use.
We recommend Drupal for enterprise-level advanced workflow applications and API integrated systems. In one example we developed online communities, seamlessly integrated with 3rd party gaming software, controlled from a slick admin console.
A great choice for small businesses. WordPress is typically less expensive to develop, offering great functionality without custom coding. We've developed WordPress sites for photographers, online stores and travel bloggers, to list a few.