I have two comments:
If showing well at a concourse type auto show is a goal, then the mirrors should be "period correct" as opposed to modern mirrors.
If showing well is not a goal, then there are many excellent modern choices, but one of the mistakes I see in regards to mirrors is using mirrors that are too large or draw too much attention to themselves. For instance there is one very expensive modern exotic car with mirrors that are so large they look like they belong on a full size truck, if they were air foil shaped the car would be capable of flight
Mirrors should blend into the lines and color scheme of the car, they should be easily overlooked or ignored, or compliment the trim, they should never exist as a focal point. Some mirrors would work better painted flat black rather than matched to a bright body color.
There are plenty of old threads about mirrors. Selecting mirrors is a hot topic for many owners. Searching the word mirror in the coach forum turns up several interesting results.