You just said a8 and s600, naturally s600 is good. It is the top engine of Mercedes-Benz S-class 6.0T V 12. A8 also has many models, similar to s600, A8L W 12 6.3L naturally aspirated. If it's a8 w 12 and s600, the grade is not much, depending on your preference. Personally, I prefer a8W 12, but I can't help Audi fans. I think Audi a8 is more business-like and calm, and I like the appearance of Audi. If it's any ordinary a8, s600 will naturally be upgraded.