I like the Gran Coupe more, though I think that the A7 is nice as well.
Looking at the interior photos, it looks like significant effort was spent on every square inch of the 6 seems to make it more styled/interesting (materials, lines, light elements, etc.). It's getting close to the point of being overly busy in my opinion. By contrast, the A7 seems to have large areas of the car that have little going on, like the majority of the interior of the rear doors. They've erred on the side of bland.
Looking forward to seeing the Gran Coupe in person.
'07 e91 328xi: SG / Black Leather / Sport / Premium / CW / Xenon / Logic 7 / Sirius / iPod
'00 e46 323i touring: (retired)