The Princess' Man - This is my favorite drama of all-time, I was anxiously nail-biting over what was going to happen next with each episode. I binge-watched it in 2 days (it's 24 episodes).
Others you should consider (in order of how much I liked them):
The Master's Sun
Scent of a Woman
The Greatest Love
I Hear Your Voice
Secret
Coffee Prince
Full House (Thai drama)
Love Me If You dare (Chinese drama)
Witch's Romance
Pinocchio