I'd hands down go with the 991 despite your power needs. That is a seriously good car
Plus VF "should" be developing an S/C for it i'd presume. Having a 500-600hp 991 with instant response would be a serious handful,especially considering they run low low 12's stock. Not to mention Porsche's are great in the snow.
The GTR and CTS-V are awesome but at a cost to comfort and amenities IMO. The GTR doesn't appeal to me for a daily driver and the CTS-V doesn't cut it for me when it boils down to the interior and the fun to drive factor..The sensation of speed just isn't there compared to the others @4300-4000lbs with the driver