The New York Times evaluates the best martini-- and it doesn't include Vodka:
"Indeed, gin is more of a thinking person’s spirit. Vodka is neutral in aroma and flavor, which is also how gin begins life. But where vodka stays neutral, gin is infused with botanicals — a witch’s pantry of roots, berries, herbs, dried fruits and spices — dominated by the piney, breezy aroma of juniper berries."