Only thing I see is School 2013, honestly I haven't watched it either but I heard it's really good and the cast is good too
Secret Love Affair, high quality!!
Kar, you absolutely MUST give I Remember You a second chance.  I will admit that the first four episodes were a bit unremarkable...I actually just read the recaps and then picked it up on episode five.  But once I finished the drama, I loved it so much that I went back and watched the first four episodes.  Plus...Park Bo Gum!!!!!
Sam-I-Am please do continue watching King2Hearts and My Girlfriend is a Gumiho. They both have Lee Seung Gi and he is such an amazing actor!! 
Suspicious Partner
I remember you! It's worth it!
Circle!!!!!! If you are more into romance, then High School: Love One!!

Please do watch Circle..it will truly blow your mind :) Best drama of 2017 so far!!!
^^^ 49 Days is a good drama 
Ktdiva3 I am definitely planning on finishing my girlfriend is a guhimo if nothing else because I love Lee Seung Gi.  The problem is that I already read the recaps so I have lost that NEED to finish it in order to know what happens.  I recommend finishing You're All Surrounded for the same reason you gave me...Lee Seung Gi.  IDK how much of it you have seen, but there are some seriously funny moments.  I love that they make fun of themselves. :)
Finish I hear your voice, it's so worth it
Sungkyunkwan Scandal, I love Yoo Ah In!
I think you should give I remember you a change.
I also dropped it first but after seeing more episodes of it I started to love it:D. Heartbreaking en bromance!!!!!! 
Secret Garden is one of the classic kdramas. Please do try it out. It's one of the best rom com dramas out there.
oMG there are so much you should give a second chance on your dropped list lol. But i guess Ill mostly suggest Doctors, You Who came from the starts and Suspicious partner