gotta drive one first
It's hard to say without actually driving the Viper, but the Nissan is one wicked fast car. I drove one on a track this weekend and it wasn't the newest version, but it was wicked fast. My lap times were identical to times I had in a 2011 turbo s. The interior on the Nissan was low rent though. You could definitely tell it came from the same family tree as a 370z. By looks alone the Viper is my choice.