Gantry 5 makes possible the generation of virtually any configuration you can think of for your site. Highly recommended.
Ease of use
The ability to change configurations, add modules or positions, create new particles to do brand new things is unparalleled.
Support is readily available at gitter for developers and in the RocketTheme forum for non-developers. Questions are always quickly answered
The www.gantry.org site is incredibly well organized and new enhancements to the Gantry framework are quickly added.