I'd recommend The Crowned Clown. I actually just finished this drama recently and I'm really surprised that I'd never heard of it before. The main lead does such a wonderful job acting that it really didn't feel like one person playing two roles. His acting truly convinced me that the characters he was portraying were different people. There's also a nice development of the characters beyond the main leads, which gives more depth to the story and made me feel more emotionally invested in all the characters.
