Bandit sign and car magnet color combo's

Does anyone have some good color combinations for bandit signs and car magnets (lettering and background) that produces the best results? I have heard black lettering on yellow is good, but wanting to get all the input I can on what has worked well for other investors. Thanks in advance.

White background, blue lettering.

What shade of Blue and/or white?

Navy blue works for me.

Is the blue and white because you are “Blue Star Homes?” Just wonderin’.