Agreed that it very much depends on the individual (coloring, shape of face and features, style in general), but I err on the side of a lighter, more subtle lip, and will continue to do that as I get older. Quite frankly, it's not the part of my face I like to draw attention to. I've always looked better with an emphasis on the eyes rather than the lips, and I have a feeling that is a rule even more appropriate as I age.
I have a friend several years older than me who has darker, more olive skin and dark hair, and she looks marvelous in dark lip shades. Always has and probably always will.