Cayenne fascia has always looked out of proportion to me. Massive black vents & rad. grill is too much.
Nu Cayenne S looks better, side vents w/ double vanes in matching body color & fog lites.
X6: big black side vents (1 side is false) & small round fog lites are also not quite balanced either.
2008 Audi Q7's or MBGL looks better then either Cayenne or X6.
But ultimately, what do we know, except what we like, the designers of each marque have spent 1000's doing their design, we , the consumer vote with our pocketbook, because of perception of the marque's prestige, features, quality, & the "total package".