I agree with most of what you said but... The 65 lacks the supreme elegance of the 600. It's too aggressive for me.
The S600 remains the absolute king: perfect mixture of class, elegance, majestic discretion, luxury and power. It is, for me, still the supreme S-Class.
The AMG is too raw, too flashy, too much. Outstanding car, but not the epitome of the S-Class as it doesn't really represent the values of it.
I would take the words of a Land-Rover big head (was talking about the RR vs RR Sport):
the AMG is an S-Class, but with a backward cap...