Hey
It firstly depends on what type of quail you will be housing, some quail like CPQ and Californians need soil or hay and cant stand on wire. Most people recommend wire flooring for Coturnix Quail. But personally I put my Quail on soil, not wire, I think they are more comfortable on it.
It is up to personal preference like JustBugged said, but only to a certain extent. I use soil and put dry grass cuttings down every now and then, you then just clean out the top layer of soil once a week (depends on how many quail you have).