Well, I suspect it's pretty much of a dead heat. Also, I'm guessing a lot depends on what's under the roadbed. I tried to do as much as I could to make the base layout quiet. All the parts of the main layout are solidly attached, no chance of the plywood vibrating on the benchwork below, etc. Then there's a layer of Homasote to add to the vibration deadening properties of the table.
First layer is 1/2 inch OSB screwed to the framework then 3/4 inch high density foam glued down using silicone caulk. Then the track is glued to the foam with the same silicone caulk. Since mine is an industrial layout, I don't need a raised roadbed for a main line.