I am working on software that is very ESRI oriented, but a future version will likely not be using ESRI software. It uses Shapefiles and Geodatabases. I'm planning on getting all of my data to Shapefiles in anticipation for future versions of the software that will likely be on Android and other mobile devices. It appears that Shapefiles are the most common datatype for features in the open-source GIS world, but what are the others, and what benefits do they bring? I'm familiar with GeoJSON and KML, but I'm sure there are others.
I would like to know all options, but I am particularly interested in dataset types best suited for storing on mobile devices (the data must be accessible without an internet connection).