Tunnel
Radiant Office
Chicago Typewriter

New dramas that you can not miss!
Go Ho's Starry Night
Hwarang
Positive Physique
Thumping Spike (I recommend watching the first season but NOT the second season)
In order of preference:

Age of Youth
Signal
My Ex-Girlfriend club
Emergency Couple
Age of Youth Season 2
Hotaru no Hikari ( you cant go wrong with Ayase Haruka and Fujiki Naohito)
Hana Yori Dango (this one is a basic for jdrama fans, imo)
N/A (Sorry I don't watch a lot of Jdramas.)
Chicago Typewriter, best drama of this moment!
Age of Youth
In Time With You
liar game
9 times time travel
Age of Youth 
Boss and Me
Cain and Able 
@Beeshooo: It's Okay That's Love & Dear My Friends!! :)
My Father is Strange 
In the order you should start:
The Guardians (you have to watch this the most)
Tunnel
Chief Kim
Voice
Bad Guys
Twenty Again
Marriage Contract
49 Days