I would agree, the Vette and Z06 are the best performance bargain, period. The Vette for 08 has apparently greatly improved their interior options. I am like you, I don't know what car to get either. I have had concerns about Audi mileage for some time. BMW always seems to better the performance/mileage quotient. Of course there is no perfect car, unless you ask those blinded by the shiny roundel. I know if the e92 M3 had DFI, less mass, steering feedback, and multi pot brakes like the lesser 135, it would probably be my perfect allround car. Still comes fairly close, if they will keep the base price between mid and late 50s.
You admit the Vette and ZO6 are great performance bargains and are good handling cars depite the fact that they both use leaf springs. Suspension technology that was perfected back in the days of the horse and buggy. Yet, the M3 gets mocked for having single piston brakes and no DFI. Of course it would be great to have these but are they really needed? It would be great if the Z06 had a modern coilover suspension but obviously it does just fine on leaf springs. So why bust the M3 when the brakes 99% of the time will be more than adequate?
We are really starting to see mixed reviews on the brakes so in the end I think its going to be subjective.