I think the Panamera is better looking. There, I said it. The Panamera interior blows away the Aston's--bar none. The Rapide exterior sucks because it's just a stretched out version of Aston's sports cars. At least the Panamera design reflects the unique purpose of the car.
I can't quite figure out what the unique purpose of a design resembling a toad with an extraordinarily large butt entails, but maybe you have a point. Who knows.