My vote is for the M45, you seem to lean towards the larger end of cars, and it's big and fun.
The A8 will not "move out" except maybe from a dig. It has authority, but it's no sports car and has a very linear power curve. If you want all out luxury, It's the winner obviously, and an amazing winter car.
We've had 2 Q45's and both were exceptional vehicles which took literally nothing but oil changes. Feels a bit more lively thanks to RWD IMO. :lolguy: