This is a debate I really don't care about. But I'm not sure what the OP is asking. Are you asking about a concrete floor with various things on top of it or are you comparing a concrete floor to a traditional joist and plywood floor?
Effects of different feet on floorstanders with a thickish rug
A concurrent thread asked for opinions on the effect of spikes and other foot treatments on floorstanding speakers with a hard, concrete underlaid floor -- what would the answer be with a moderately thick rug over plywood?