I have Cesium blue and love the color (specially with black optics package and black wheels), but it is attention getting, maybe even more than the red. I don’t own either cars but here is my opinion anyway:
The red is a nice red, unusual, eye catching. But I do wonder whether it will age well over the years. It may, but it is a “fragile” color in that it shifts a lot based on ambient light. This can be good or it can be bad depending on your view.
The gray is elegant, pretty and safe. And I would suggest is the second or third best color for the car shape.
So in a way you can’t go wrong with either, and you will probably have some “regrets” whichever you choose. So you can’t go wrong really.