My favorite color has always been purple. But I may change my mind.
Green. Not any particular shade you'd find in a tube of paint, but the green of the living world. Here down in the Chattahoochee river valley I can see the tops of the trees rising on both sides, from the tender green of the new leaves to the darker greens of pine and fir. It's so restful to the eyes. And it never clashes, even when you have flowering trees budding purple and white in random spots. Soon the honeysuckle will be in bloom and then it will all smell very good.
There should be a god just for chlorophyll.