Depends where you live, you must live somewhere with warm climate all year around. If you are concerned about space you could use rigid insulation(1.5",2", 2.5") to bring up your r value with min space.
Studs are more preferable. You can run receptacles in them and mechanicals. You also need a vapor barrier in the basement. Insulation is a good idea but you can just butt fiberglass up against the concrete. Concrete is like a sponge and you'll have moldy fiberglass in no time. Foam is a better idea...closed cell, because it will insulate and create a vapor at the same time.