I will have to go with the 68 SS Chevelle. I owned one that was one of the very first built with rare SS side marker lights. It had three options.
Posi, tinted glass and AM radio. The car was purchased to street race the original owner told me.
What I found interesting was it came from the same dealer my Fathers now Rare Chevelle Concourse. My fathers car was sold 3 days before my car was and it was in the show room when my dads car was delivered. I was only 6 years old but I actually saw the SS I would later own years before I would own it.
Now that I'm done bugging Haggerty staff about typos they made, I would take the Impala. I'm well aware how rare and special the SS 427 package was compared to just an SS with a 427. One car I've always wanted was a '69 Impala SS 427 hardtop with 4 speed.