I'd vote for a stand, though of course placing it on and off pretty much anything will allow you to try both.
My gut feeling is that the speaker will sound a bit chesty when sitting on the floor due to boundary-effect and the speaker's low-end ability.
If you do indeed find a stand of a particular height is preferable, it's easy enough to build something simple and virtually invisible until you have the time or the money to replace it with something better. Maybe some colored (black?) milk-crate-type things from Target would work for awhile....
