Who knows what the future will bring.
I have a Heritage, but I think Yellow is more rare.
But, in the future, maybe Red will be the color with the best resale.
Maybe the GTX1 will be worth the most, or worth nothing. It's all about what the buyers of the future are willing to pay.
I don't think stripes or no stripes will make a big difference, but it may, for some big collector. Adding the stipes later is not the same thing. Collectors will want an original (IMHO), they way it came from the factory. Any modifications that anyone makes, be sure to keep the original parts. I'm going to keep my stock muffler and the plastic oil caps....
It's your personal choice, buy what you want and like. Or buy what you feel is the best deal for you. You could probably wait 3-4 years and get one for half price.
Would be nice if Ford put some more hype behind it. That would certainly make the next supercar, if any, more saleable. If they work at it, the Ford supercar could be just as exclusive and hard to get as a new Ferrari.