Blue!
I mean, how can it be anything other than blue? The color of the sea whence life emerged, or if you prefer, the warm kiss of the sky over Eden. A soothing, rich blue, ensconcing us in its velvety serenity. The color of a beloved, faded pair of jeans, your companion through the triumphs and tears of years gone by, with the comfortable promise of safety and warmth in the coming day. Blue.
Unless red. Red’s cool too.