I think it depends on what's best for you. I have both a coup and an aviary on the ground. The quail in the aviary have much more entertainment. Bugs to chase dirt to dig in and Sun to bask in. They literally never go into the coup. I think it makes for happier birds[IMG]
I also find that I don't waste and feed when they are on the ground. All the feed they chase out falls to the ground and they end up scratching around and eat from the ground. When they were on wire all the food fell through the wire. I wasted cups of feed a day.