My least favorite out of the 3. No doubt the E63 is a beast now, but that is not what I'd consider a good looking, especially next to an A6 and 5er.
Current: 2008 BMW M3 Sparkling Graphite/Bamboo Beige/6MT. 1999 BMW M3 Techno Violet/Dove/5MT. On the list: BMW M2 Long Beach Blue/Black/6MT