Grey. When I was younger, I was rather fond of blue, but getting older and wiser, I found other colours to like.
But blue, the cold of the lighter colours, the colour for the shadow on snow, the sky in the afternoon a summer day, or in the opposite site of the sunset a winternight. The warmth of the soft nuances just before it hit purple.
Red, fierce and warm, like blood and life and fire. Colder, merging a little with the light blues of the sunset sky, getting a colder glow.