I'd take the CLK Black Series in a heartbeat, although I'd probably never love the 7 speed auto in it, nor the "low" 7200RPM redline.
But the rest of the car is absolutely teh sechs.
I agree with the guy above who'd take the 911 (I'd personally go for the GT3 though) if we threw in all cars at that price point. And for that matter, I am willing to believe the M3 CSL - though it may well not make it to the states again - will probably be better than the CLK63 Black Series in just about every way as well.