There is no right answer, look around where you live. In our village most doors are wood finish or if painted they are muted greens, greys etc with the odd dark blue or maroon. That fits the buildings and look right with the local pale cream brick. In a nearby new development, all trendy townhouses and apartments, bold colours look good, tangerines, deep lilac, fits the place well. In the old bit of the city it's mostly serious and stately, maroon but mostly deep greens and blues, quite a lot of black. A seaside village I know well has a bonkers mix of yellows, greens, pinks, purple etc but it works there, wouldn't work everywhere. Maybe have a few evening local walks and see if you spot any " oooh I like that" moments. That's what we did to choose our new doors 2 years ago. If you are handy with things like windows paint or similar, edit a picture of your door by filling in with different colours. See what works. Maybe go on the Solidor website, pretend you are looking for a new door, use the door designer feature, pick a design similar to yours and just scroll through the different colours available.
Another thought is the local atmosphere. We get quite a lot of wind borne dust off the fields nearby, all light. Light doors look clean even if they aren't. When I lived in Moss Side Manchester in the very early 70's anything which wasn't grubby dark grey soon got that way if it rained because we still had lots of coal fires and traffic. Again, a few local walks will tell you a lot.
Choose what you like but remember you might want to sell the house one day so don't go too far away from the local norms.
