We don't have reliability data for the Jaguar and BMW 6-Series. Newer is definitely better with these brands, though. Both feel considerably larger and heavier than the other listed cars.
With the Audi, we have just a few reports of carbon build-up across all model years, so it doesn't seem common. Carbon build-up was much more common with VW/Audi engines in earlier model years.
With the BMW, I found just one report of a complete DCT failure, but we probably don't have more than 20 of them in the survey. We have more reports of relatively minor issues with the pan or shifter. The M3 is another level of performance from the other cars you have mentioned, but unless you have a road that requires the car's full potential there's little special about driving it. Might the 335i (which is actually stronger at low rpm) also work?
One you haven't listed is the Infiniti G37. It's more attractive and performance-oriented than the Lexus, and should be nearly as reliable.