Your top 3 favourite K-Dramas 
Optional: Include a brief description about why you enjoyed each drama so much x
just 3? not even 5? that's kinda hard to choose.. Hahaha but mine would be the following..

1. Queen Seon Duk
2. Secret Garden
3. My Love from the Stars 

... they're all 10 for me. And I have lots of favorite dramas with 10. XD
1.  Faith
2.  Healer
3.  Fated to Love You (K Version)

the first two because they show a really good version of relationships.  Lots of communication, cooperation, hard work, trust, and faith - there's no need for confessions.  They're flawed wonderful human beings who you carry with you and think about during your day when you're doing other things

Fated to love you...I was really unsure about it at first, but by the middle where the standard K-Drama crisis happens, I had to pause for a week because I knew I would hurt so much for the characters because I liked them so much; their pain would hurt me.  It's got really silly fantasy elements but the two leads are both such great people.

Honourable mention to Age of Youth.

Every good drama has something extraordinary... hard to choose only 3 but..

Cruel City - 10
Jumong - 9 (is here probably because I watched recently, but still good drama)
Bad guys 10

- Comrades   - 10
- Road Nr. 1  - 10
- Six Flying Dragons - 9.5

Considering my ratings, these would be my favourites. Though I still have plenty of series to watch! :)
@Naksken so true! I loved that in Healer, too.  How CYS reacted when she learnt about the real identity of Healer-ya was the best thing. It was one of the things that made Healer one of my favorite dramas of all time. :)
1. Cruel City
2. Age of Youth
3. Misaeng

All have a score of 10. They're all masterpieces to me
@Anniee, she has faith in her intuition, she has faith in him, even though she's scared and hurt she says "even if you don't find it, still come" - breaks my heart in the best way!

I love a good relationship that doesn't need explaining or confession (real life isn't like that).  Healer and Faith are the only ones I've seen, I want more.  Song Ji Na needs to write another drama. 
49 Days
Two Weeks
White Christmas
All rated 10/10
Another Miss Oh
Age of Youth
Dear My Friends

...all rated a 10
-W (10)
-City hunter (9.5)
-My gf is a gumiho (9)
MARS (Taiwanese) - 10
1 Litre of Tears - 10
Kill Me Heal Me - 9.5
Goong (9.5) 2006
Delightful Girl, Choon Hyang (9.5) 2005
Wonderful Life (9.5) 2005

I can't give the perfect score because nobody perfect. Hehehe.... peace
even an old dramas, its really give me a good impression until now.
Healer
White Christmas
I Hear Your Voice.

I have watched these dramas multiple times.   I love a storyline that isn't completely predictable.  I also love strong , well written characters that aren't two dimensional.
1. angry mom.
2. oh my ghost.
3. 38 task force.