This is a difficult choice for me. The C63 presents a full-fledged monster when viewed from the outside, but it really is a pretty tame animal considering its automatic transmission. Don't get me wrong though - it having the most power of either the M3 or the RS4 already makes it quite a devil. But I just can't put my finger on it - sports car or luxury cruiser? Or both? Well I think the C63 does both very well.
The RS4 has less power, looks a little more tame. But it'd probably sell far less than either the C63 or the M3 - and for that reason, I'd probably take the RS4. It's a special product. It's not just a fast car, if you want that, you got an S-car. This RS model is born and bred solely for the purpose of sporting intentions. And for that reason it's possibly Audi's most virile beast to come.
I look forward to the new RS4 with anticipation.