The GT-R is definately a better value for money racer. It will always be quicker, but I'm just a fan of the old school RS's (replicas). NA, lightweight, simple cars with a heap of character. But I'm a Porsche fan boy, and if I wasn't then I'd go a GT-R for outright pace.
A mate of mine has a white 73 RSR replica that he runs with the Porsche Club. It does 23's around Sandown, and 50's (I think, could be a touch less) at PI. It might not be as quick as a lot of the GT-R's, and it's worth a fair bit more than a lot of them, but I'd rather be belting around in that