New Challenger vs Original

Actually the whole comparison between the two (new vs. old) is ridiculous. There is no comparison, either way, other than a slight resemblance. You have to choose what type of car you want. I have always liked the 70/71 Challenger the best, especially the 71 but having owned a few E-bodies I know they need a lot of work to be fast or to handle and not squeak you crazy. I really don't like the Challenger after 72 but I wouldn't kick one out of the garage. I always preferred my A-bodies.
If you really want that old car, get it. I would also recommend that you pick up a Charger R/T as a modern daily driver/fun car. There are a ton of mods you can do, they are cheaper than a Challenger and you can beat them silly. The only down side is that they are all automatic.