So.... this might seem a little bit stupid, but  I found out, that I currently finished my 299th drama. I want the next one to be something special. So I want to ask my dear MDL friends to help me find some awesome drama, that I havent watched yet. Something really good, or something that you really liked. Thank you for your help :)

i picked one from your on-hold 

Moon Lovers: Scarlet Heart Ryeo 
I recommend My Lawyer, Mr. Jo, I really liked it.
Shine or Go Crazy. It's a Korean period drama (Goryeo I think?).

Jang Hyuk does a good job playing an aloof nobleman and Lee Ha Nui does a great job playing an interesting and complex woman (though she's not the leading lady - she does get her fair share of screen time).

But I'm biased to that show mainly because of the performances of the two people I just mentioned.
I'd suggest something fun and light-hearted, looked at your ptw and totally rec: My Boss My Hero, that drama is hilarious and a good watch ^^
Ooh, two of my absolute favorites are on your PTW: A Man's Story and Chuno.  So of course I would say go for one of those :)

Congrats on watching so many dramas! haha
I think any person that enjoyed Age of Youth, would really, really love Dear My Friends.

Also, Nirvana in Fire is epic enough to be a FABULOUS pick for a celebratory occasion. 
if you enjoyed Reply 1997 i think you will surely love Reply 1988 :)) this drama felt quite special to me :D