When you say Corvette, I assume you mean the Z06... Personally, I'd get a Z06 because they're so badass. Of course, Vipers are the flashy cars, so if you want a car all people, including unknowledgeables, can drool over, i'd go for that. Only some people will know what the Z06 is...Or, if you prefer European cars over American muscle, any of those is great, I don't have a particular favorite.
Here, I'll make a list of what I would get in order from most favorite to still-favorite-but-not-as-much-as-most-favorite (none can be considered a "least-favorite".)
2006 Corvette Z06 OR Dodge Viper (tied for first) 2002-2004 Porsche 911
2003-2005 BMW M3 OR 2003-2005 Mercedes CLK55 AMG (tied)
2007 Mustang GT500
2006 Cadilac XLR