Hmmmm… Best drama ever : Healer. I think Healer is just amazing, like Ji Chang Wook is perfect, his acting is 
I love him so much!
Best old drama? Coffee Prince.
My favorite drama of now is D-Day and i think it’s going to become the best drama for me. 
Pinocchio is awesome.
My Love From Another Star is great.
Sassy Go Go (Cheer Up!) is starting to become my favorite.
I would say for the first one i have two and its Faith and Healer. For the second one is Heartstrings and right now its a China drama Love me if you dare, Oh my venus and Bromance.
There will be always more than one 
I can’t really choose between all the dramas, but here are some of the best ones I’ve seen up till now.
Fantasy based: My love from another star, My girlfriend is a Gumiho, Orange Marmalade, High school Love on.
School: The heirs, School 2015, Reply 1997, Dream High, Sassy Gogo.
Old dramas: The Moon that embraces the sun, Heartstrings.
Gender-bender: You’re beautiful.
I find that k-dramas usually have the same plot, and the most common ones are “the rich guy falls for a poor girl”, “Living together”, “The bold and justiceful girl”. If you are somewhat for d of these, you should go for fantasy based dramas.
SECRET with Ji Sung
LIE TO ME
SCENT OF A WOMAN
HOTEL KING
MASK
CITY HUNTER
SECRET GARDEN
PROSECUTOR PRINCESS
PROTECT THE BOSS
HEALER
KILL ME HILL ME
THAT WINTER, THE WIND BLOWS
MASTER’S SUN
MARRIAGE NOT DATING
and it all started with BOYS OVER FLOWERS… by the way all above are great to watch!
there is so many of them it’s hard to even think or list them all but anything from Ji Sung is great and I like mature k-dramas when plot is unique and keeps me marathon the whole thing!
Oooh…
1: I’d say as of now the best drama I’ve seen is Healer
2. Hummm… Even though the last episode just dropped the ball, I’m going to say Iljimae.
3. For this I’ll say Remember, the Yoo Seung Ho drama that is currently airing. Only episode 1 has been released so far but it looks promising. It’s also pretty much the only drama I’m watching right now.
my answers have changed since the last time i replied, lol. now, it’s:
all-time favorite drama - well, still misaeng. but i might have to add what happens to my family? i’m also tempted to add cheer up (sassy go go) because it elicited more tears from me than i knew i had inside me.
best classic/historical drama - dae jang geum and perhaps gu family book, but mainly because i was so impressed by the ingenuity of lee soon shin.
favorite ongoing drama - remember. everything about it is perfection.
favorite taiwanese/chinese drama - nirvana in fire.
Ever? hard to say, I have watched over 600, I could say my top 15 I think… Let’s see, City Hall, Greatest Love, Cain and Abel, Save the last dance for me, My Girl, How to Meet a perfect neighbor, Snowflakes 2000, my name is Kim Sam Soon, Personal Taste, City Hunter, Bride of the Century, Coffee Prince, Gu family book, Life is Beautiful, scent of a woman, iljimae, Sorry I love you… I still have about 20 more that I think were well written and good over all, and there are those I like just because of the actor… too hard to choose one when just this year I have watched over 30 so far and I have loved about 7 or 8…
Oh I think Cain and Abel was my first drama with So Ji Sub and I loved it (and him) ! They were cute Han Ji Min and him. The story was nice.
i dont really have ONE favorite so i will just say the top few best
After looking through the comments, maybe my preferences are odd. I don’t see my favorites mentioned. I have so many that I love, but I guess these are at the top:
That Winter, the Wind Blows
A Thousand Kisses
Baker King Kim Tak Goo
What Happens to My Family
Padam Padam … The Sound of His and Her Heartbeats
And the newest would definitely be, The Lover. Most honest, true to life I’ve seen (18+)
For Taiwanese, it would be:
It Started with a Kiss & They Kiss Again
The Rose
heeey!!!
I’m relatively new to kdramas (been in the dramaland for 2 years not, that’s still new? I guess?) but for me,
Best kdrama- I am going to pick one airing right now, Oh My Venus. What I love about this drama is that the male lead always says that losing weight doesn’t have to connect with beauty, it’s more connected to health! Also, its So Ji Sub. He is bae!
hmm…trick question, because I have not watched any old ones. I’ll say love Rain!!! Loved the main leads!
Again, Oh My Venus. I also love the taiwanese drama Marry me Or Not!
i really loved it and i still do…<3 
I am also watching my first chinese drama Love me if you dare, and so far i think its awesome 
my favorite drama is “Secret Love Affair” 
Oddly enough my favorites have been Japanese and Chinese dramas. Way back over 10 years ago. Not sure why I don’t watch anymore of those type of dramas. I’m watching mostly Korean now but don’t know if any of them are favorites. So I won’t list any. xD
I haven’t really watched a lot of dramas yet and there’re still a few I want to watch but my favourites till now are Kill me Heal me (I just finished watching it and I love it so much I absolutely recommend it. It is really well done and the cast is great!) Another drama I really liked was Pinocchio Not just because of my crush on Lee jong suk but also for the message the drama gave about the media. Another one I really liked was Cheer up!/Sassy Go Go! it told a lot about the feelings, problems and thoughts teenagers have. But as I said there are some more dramas I’m looking forward to.