On looks, I'd have to agree, definitely the Aston, but that's also double the price of the Panamera.
I'm not a big fan of the Panamera's looks myself, especially the back, but it kind of grew on me, I see them by the dozens in Germany. It's just that apparently they're a ridiculously good drive. A lot of people will jump to the opportunity to drive a big Porsche saloon, as they never used to make those.
I honestly don't know what I'd do if there were a 7-series and Panamera infront of me and I could pick, as you're in the car when you're driving it.