The Ur-Quattro wasn't actually such a revolution as people make it seem. It wasn't even the first 4wd car by many years. It was just the first when rules changed which allowed 4wd cars to enter again.
It was beaten in a championship by the RWD Lancia 037 and then twice by the AWD Peugot 205 Turbo 16 E2 And when the Lancia Delta Integrale came along for it's six back to back victories, Audi was nowhere.
There is no true best AWD system, most are very different and specialized. And if I had to pick best all-round it still wouldn't be Audi it would be the new system in the new Range Rover Sport (which is finally worthy of the badge.)