Which is best for stacking? Gov't issued silver (ASE) or generic rounds? Or if in combination, what percentages?

Been stacking for a handful of years now.... started out with ASEs as annual b'day/Christmas gifts for son, bought a few for myself, caught the fever and proceeded to buy mostly non-gov't issued rounds/bars/etc. Several reasons for stacking.... have a decent stack, more generics than gov't issue, and have been wondering if I should concentrate more on the gov't issued shiny ....

Would appreciate serious responses, pls.