This is a great and tough question! I think it ultimately depends upon the type of car you are looking for. I now own both an old school Challenger and a new one.
They are both great, but in their own way. The new ones are super comfortable, very smooth/quiet, very responsive, sytlish, and loaded with lots of creature comforts even in the base model I have. It's very fun to drive.
My old school 440 Challenger is also fun to drive, but in a very different way. It's more like a loud, flashy car with the graphics on the hood and side that scream 70s muscle car. This makes it fun in its own right. It's also very rare, as I don't see vintage Challengers on the road in my area.
In short, I recommend both...