Old vs New:
SLS AMG or 300SL; 300SL, because it's worth more and I prefer the styling of it a bit over the SLS.
Jaguar E-Type or F-Type; I think I'll go with the F-Type. It's easier to live with and I personally think it's better looking than the E-Type (though, I still think the E-Type is a great looking car, though I prefer it as a coupe).
Dodge Challengers; The classic one any day of the week, it's lighter and more nimble probably than the modern SRT8. Also, while I still sort of like the modern one, I don't like the fact that Chrysler made it so bulky and sluggish compared to its pony car rivals.
Mclaren F1 vs P1; I honestly really love both, but I have to take the P1. I truly believe it's a great successor to the F1 in terms of performance and engineering. I also think it would be easier to live with tbh.