if we're going to think in terms of a single trait, i'd say clarity. man or woman, no difference, i love a clear person. because clarity brings naturalness, honesty, transparency, sincerity, humility, empathy, and genuineness along with it. just as a clear person won't bother with empty matters, in their relationships there's no inconsistency, scheming, or indecision either. a clear person is plain, simple, and natural. they're a genuine person, free of affected behavior and staged emotions.
not confusing self-confidence with narcissism. having a quiet self-confidence, not trying to prove themselves in whatever setting they walk into. they don't tell you "i'm like this, i'm like that," you notice it over time.