Honestly, keep the color as it is. The other colors just look like a clash. Black is actually a great color to have for a front door. I wish I had colors that would support a black door. It's a fantastic, neutral backdrop for any seasonal wreath - like in the fall the color orange clashes with so many colors, but black looks great with all colors. Also, black makes your house look more expensive. For added colors, just put out extra potted flowers (like red flowers) at the top of the steps and hang colorful wreaths throughout the year.

P.S. The only other option would be to paint the shutters white and have a white front door, which is also a very classic, timeless look.