Bee Quick is the nice smelling one that is supposed to be nothing but essential oils. It smells like Benzaldahyde, which is the chemical used to make artificial almond flavoring and used to flavor Maraschino cherries. I have heard reports that Benaldahyde works in a similar fashion to Bee Quick, but have never tried it myself.
Butyric acid is often used to drive bees out of supers. It smells like the "essence of vomit". The bees seem to hate it almost as much as I do... it is sold under the brand names "Bee Go" and "Honey Robber". Honey Robber smells like cherry flavored vomit...