Since I recently went through this I'll give you my .02. I still have my first car a 1970 Roadrunner I bought used in 74 and wouldn't trade it for any car, but I've always wanted an E-body with Cuda/Barracudas being my slight favorite. I began to look last year about possibly buying a new 6 speed Challenger, hadn't really decided on whether it would be an RT or SRT8. The RT's better gas mileage, lower price & the classic's stripes were big pluses, the SRT8's better handling wheel/tires, brakes, exclusivity were its big pluses to me. Big minus on the SRT8 was the Fuel 'tax' you have to pay up front due to its lower MPG.
Then I started thinking about just how much I'd drive the new Challenger. Unlike what others have said, especially an SRT8 would be a fair weather decent parking space kind of car for me. If I couldn't be sure that I could keep door dings off of it, etc. I'd probably just drive my truck instead. So I asked myself do I really want to spend $38-46K on a new Challenger or would I rather have a classic 'pony' car like a Barracuda that I've always wanted. I started looking around on found a decent 73 Barracuda 318/auto car with A/C, PS & PB that seemed like the perfect solution for what 'I was looking for'. I got the guy down to $8k and bought it a few months ago. Ever since I've been gathering parts to restore it, but its still going to be more of a driver than a show or race car. That I'll leave for my 70 Roadrunner. So for me the older car made more sense, but to be honest as I've seen more & more of the new Challengers on the road, there's a lot to be said for them as well. Knowing me as I do, I probably have 'one more car' in me so I wouldn't be surprised if I still end up with one of the new Chally's before I'm done.
What do you want to do with the car?: Transportation, car shows & cruises, learning about working on cars a little, having something rare to drive, how much does comfort matter, performance, dependability, etc.
This may sound simple, but I'd make an honest list of pluses & minuses for each car and see if that doesn't help you make up your mind. Either way you'll end up with a great car.
Good luck, Jim