What are the differences between Audi's Quattro and BMW's xDrive AWD systems?

I'm in the market for a luxury AWD car and I'm considering either an Audi or BMW. Both brands have their own AWD systems, but I'm unclear on the differences between them. Can someone explain the technical aspects of the Quattro and xDrive systems and how they perform in different driving conditions?

Audi's Quattro system uses a 40:60 front/rear power split and a center differential to provide superior traction and handling. BMW's xDrive system uses a front/rear torque split that can send up to 100% of power to either axle as needed.

In terms of performance, the Quattro system is more rear-biased and offers better control in snow or slippery conditions. The xDrive system is more front-biased and better for on-road handling. Both are impressive in their capabilities.

In terms of maintenance, the Quattro system requires more frequent servicing due to its more complex design. The xDrive system is simpler and easier to maintain. It's a matter of weighing the benefits of performance versus convenience.