Welcome aboard and congrats in advance on your upcoming purchase. As an owner of a V6, I can tell you that it has more than enough grunt to get you into trouble but if you want more get up and go that you're probably better of with an R/T. As far as winter goes, I'd invest in a second set of takeoff wheels and good snow tires for it. As long as you're responsible and take it easy you'll be OK even with heavy lake effect off of Lake Michigan.
Just based on your commute, the V6 will be the star as far as fuel mileage. I commute 60 miles per day in mine and see average fuel mileage in the 31-32 range running at 70 on the highway.
I'd drive both and see which one you really like.
2014 Charger R/T Blacktop
2015 Challenger R/T Scat Pack
I can teach it to you but I can't understand it for you.