I enjoyed many dramas last year, so it's hard to choose one.
However, in my opinion,
Natsume Soseki no tsuma was the best drama of 2016. The life of Kyoko, wife of the famous writer Natsume Soseki is incredible, and sad. I didn't know Soseki was so mean with his family. This drama informed me a lot, without being boring at all. The acting was really good. Machiko Ono did a fantastic job as Kyoko. She was able to play this changing character, sometimes cheerful and brave, and sometimes extremely sad because of her husband. As the quick-tempered Natsume Soseki, Hasegawa Hiroki was really scary.
But the drama that I enjoyed the most (which is different from the best drama) is unquestionably
Boku no yabai tsuma. Every week I was waiting for the new episode, I was completely hooked. There were many twists in the plot, and I wasn't able to predict what would happen next, and that was really entertaining.
Yes, 2016 was a good year for jdramas in my opinion.