Gen 2...and this one may be up for sale!
gabe
I personally love the GEN 2's. I won't own a sports car that is a convertible.
The hood and front end is what made the viper. They ruined that with the SRT's but gave it a lot of nice upgrades. Keep in mind though, older vipers are more expensive to replace parts on (20k just for the hood from dodge) so if you have any kind of spill in it and it touches the hood it's most likely totaled.
The SRT's panels are readily available and much easier to come by. The hood wow's people when you open it. Point blank. I can easily miss an SRT driving but to miss a GTS or Gen 2 its hard. They are very bulky looking and have a more aggressive look, in my opinion.
you really can't go wrong with any Viper.
I have owned Gen I, II, and IV. I've never owned a Gen III but I think Gen IV is a close enough sampling.
If I had to choose one keeper out of them all, it would be a Gen II car...just because of the exterior styling. That would weigh very heavily in my decision.
However, you really can't go wrong with any Viper. Good luck in your search.