Technology has not gotten to the point that you can keep color in vinyl. It absolutely will fade. I sell against vinyl in the business I am in merely by having photos of vinyl over time.
It is a great low maintenance material, but it does not take UV well.
Either treated or cedar will have the best chance, but even those will require some type of maintenence eventually. There is also new materials that are a combination of reclaimed materials and possibly some plastics that is to be all the rage. It is used in decking and has the feel and look of wood, but is supposed to be more resistant to rot and UV. Trex is the trade name I recall.
Look up a material called Kebony for an all wood alternate.