What color do I paint the front door?

I think a light aquamarine blue will look nice!

I'd go a cheerful yellow or welcoming red...You want the front door to stand out. And remember the flowers.

I find that I do not notice the roof color, not sure if others ignore it automatically as well. I wouldn't worry too much about that color.

Really, with tan siding, I think the sky is the limit. I do agree to remember your flowers. If you have a garden by the door, you have a built in palette. You can easily pick one of the flower colors for the door color. Or, if the garden has annuals in it, choose the color you love and then pick flowers to match the door. I also agree you want the door to stand out, be welcoming and make a statement. Have fun with your decision!

If you like the blue of your roof, go a much darker shade of blue that complements roof. I have seen this done in Holland and the effect is stunning.