Ah, such a wide ranging subject.

Depends very much on the man and who he is to me.

Broadly speaking - Humour, intelligence and good conversation, curiosity about life/the world, tolerant, open minded, caring and gentle. That goes for romantic partner and friends (my son is like that too).

Solely on a physical level for romantic partners, I'm not narrow about physical appearance, it's the soul I fall in love with - but I love my husband's blue eyes, the twinkle he gets in them sometimes and his cute smile. Also I love the smell of his skin and snuggling up to him.