ipsedixit, You sounds like you are in love!
As a matter of preference, I also like the 6GC better. But then, the Panamera does have a good presence. Case in point, a Panamera is more likely to be valet parked in front of a hotel than the 6GC
But I share your feeling towards the 6 GranCoupe. When I had my F10, I put so much effort to change its appearance (M-tech kit, Morr wheels, rear spoilers, whiteline rear lights, color matching the xenon to the LED corona, color matching the fogs..... etc). With the 6 GranCoupe, it is a matter of spending effort to search for what will enhance the look of the 6GC, and as of now, I cannot find any! Well, except for maybe wheels, which I went back to OEM 356 Liquid Black. The 6GC just looked perfect! Adding anything extra always feels out of character for this car.
But then, the Panamera GTS is supposed to be enjoyed by driving it, more than looking at it....
If I were a sports car fanatic, living by listening to the roar of the engine, Panamera GTS rules. Everything else, the 6GC is pretty much equally as good.......