Nirvana in Fire 

I know not all people in the world are in love with this drama, and everyone is entitled to their taste and opinion, but... for me it's one of the greatest drama experiences ever. 
Please give ProDai a chance :)
even Yamapi is pleading...

^^ I would tell you to give Atashinchi no danshi and Dragon Zakura a second chance! :)...well atleast Atashinchi no danshi :D
^noted :)

whoa Hana Yori Dango was dropped! but it was classic...
^^  :)

Ohh I didn't hate Hana Yori Dango, but I had watched the K-remake of it and so I can still remember the scenes in the drama, so I got a bit bored.. 
OMG First I wanted to write Boss&Me because that was just a really super fluffy lovely drama
but then I saw Shut Up Flower Boy Band o.O 
why... I loved it so much that I recommended it to everyone... even if they did not watch dramas haha 

Ok I have to admit that I loved the music and the bromance while the story was pretty common 
fabulous boys is a really good drama at least for me i loved all the versions, and this one is so cute , the ost are awesome, and it's just worth it!
aw you should give cruel romance a second chance. They got some great skinship and chemistry. Definitely worth the watch
@TheGrowlingStomach Give Cruel City a second chance.. :)
Signal or Misaeng, great dramas!!
From your on-hold list:
Rooftop prince
The Moon that Embraces the Sun (I know the part with the child actors is awesome, but give it a chance to the adults it gets better)

My Girl (One of my first kdrama. Try one or two more episodes, the comedy is less forced after that)
W (It could have been better but it's still a pretty okay drama.)
The Princess' Man is WORTH IT. 

It really amps up after the episode in which you dropped it; it's one of my favorite dramas of all-time. 
@ViolinGal chinguya, I am impressed you haven't dropped any dramas. Well in your on-hold list, I suggest you to give KING 2HEARTS another try. It is one of my favourites. The story is good and the actors are awesome. The chemistry between the leads is great. 
@kimchiinitaly I'm surprised that two dramas that left me a deep impression were in your dropped list! Delightful Girl, Chun Hyang, was one of my favourite rom com ever and I have watched it thrice. The drama is old and the fashion is outdated but the male and female lead gave me such heartwarming experience that I could not stop watching them. The drama was full of meta moments too which just added a layer of hilarity. It also kinda gave me a better idea of the Chun Hyang folklore because this drama was kinda based on it. The antagonists might be infuriating but that's what made you root for the main leads. Try it again and perhaps you will enjoy it more?

Ghost is good!!! I like how cyber crime is being used in this drama because it shows how vulnerable we are to cyber crimes. This drama left such a deep impression in me that up till now whenever I heard "Phantom of the Opera", I will freak out. I think the drama started to pick up the pace after the faces were swapped, so just hang in till that part!