Traditional brick is rarely one color. Stand close and you may find rust, violet, charcoal and a little cream in the same wall. That variation is useful: it gives a new front door several possible connections to the house without requiring an exact match.
Choose which existing element you want to respect most. It might be the symmetry of the windows, the width of the surround or the quiet formality of a straight approach. A door with a restrained panel arrangement can preserve that character while feeling cleaner than a heavily ornamented predecessor.
Consider the surround as a separate decision. Painting the door dark while leaving the trim lighter can make the opening legible. Taking both into a similar tone creates a more unified, recessed effect. Neither is inherently more modern; the right answer depends on how much contrast the elevation already contains.
Keep the first proposal simple enough to judge. Change the door in a photograph, but leave the landscaping, sky and lighting untouched. A dramatic rendering can flatter almost any option. An ordinary image of the actual house is a more useful test.
Photograph credit & license
A red door on Gayfere Street - geograph.org.uk - 6088271.jpg by John Sutton. CC BY-SA 2.0. Displayed with responsive cropping; original downloaded image retained.
A red door on Gayfere Street by John Sutton
Photographs are drawn from an international architectural reference collection. Their use does not imply a Side Door installation or endorsement by the photographer.