Great White Tower if you dont mind a male lead, the masterpiece in this ambition genre
Empire of Gold, not much on romance
Queen Insoo, batshit crazy ambition, main female lead is scary
DaeJangGuem, revenge gradually turns into career excellence, she excels in what she does breaking the norms in two different entirely different fields. Subtle but strong romance
Actually KimNamJoo plays a strong independant woman with mature romance and one of the best couples ever in "my husband got a family" but it lacks strong ambition