BOTH OF YOU ARE VERY USEFUL BUT TO DECIDE WHO IS MORE USEFUL IS VERY DIFFICULT
The concave mirrors are used as makeup mirrors because when the face is held within the focus of concave mirror then an enlarged image of the face is seen in the concave mirror. They are used by dentists because they are converging mirrors and reflect light to the focal point. They are used in solar devices to collect heat and radiations. Heat radiations from the sun coming from infinity are brought to focus by concave mirror in its focal plane.
Convex mirrors are used as rear-view mirrors in motor vehicles because they form virtual, erect and diminished images irrespective of distances of the object. It is this wide-angle field of view which makes convex mirrors highly suitable for security.