OK, what are the advantages of each for residential use.
Split systems are what are most always used. It requires longer and more skilled installation. Plus the attic seems to be the worst place for the evaporator coil to operate and be serviced.
Reading here, a good installation is a must. So it seems a package unit would be simpler to install, easier to service, and in a more comfortable environment.
Since I've never seen a package unit for a home, there must be an obvious reason.