I think I would leave them black if you are leaving the other colors as they are... solid double doors are a lot of space ! I would look to add color and interest in other ways-- large planters/flowers, a trellis or something between the large area between the 2 front windows, a larger, more interesting light. most of the landscaping looks immature and doesn't do much to help 'dress up' the house-- some transplanting and changes with the landscaping will help to lessen the focus on just the front door and improve the house's appearance. then, when you've done some changes, it will be easier for you to decide what would look best for the doors...

I would check a sample near both the stone and wall colour first.

I like the blue examples that @houssaon shared, but look at colors you love. Also consider if those 3 posts are necessary or not, or could they be reduced to one that is thicker? Could the lower half of the wall on the left be painted the color of your house trim to brighten up the entry area? And could those gutter spouts be repositioned better for both drainage and appearance? A fun project area and will be real nice when you're done.

absolutely no shutters. Why muddle up the look of the exterior when he already has 2 siding colors, with 2 diff siding materials, brick, white trim and a charcoal/greenish roof? here. does this look good? (give me a pic straight on and I'll photoshop something better, but it still won't look good! for the front door, He might try looking for a deep olive green with some bronze undertones Like this color on the left replacing the bright bench w/a wood verision, and getting some numbers clearly displayed. you'll have to enlarge this to see everything He could always paint that white one, add some colorful outdoor pillows. I also like all of these wood and copper accents, along w/these paint colors, address plaque, and even a slight limewash on the brick I know you said he doesn't want to paint. but a very light limewash w/Romabio would give this similar effect. (AND, if will completely wash off within 72 hours if he doesn't like it. there is no upkeep w/this, it's natural liime and will patina w/time. Just a suggestion) could also go darker w/the Urbane Bronze, Iron Ore, or one of those dark bronze/black tones Or, maybe you want to go w/a brick color front door. maybe a door w/some lites in them rather than solid this door style might be nice. you could even have smaller glass panels.