Okay so I started watching about 2 yrs. ago and I have only seen about 25 dramas. I need a list of dramas that all k drama lovers should have watched. I need to know if I am watching the best ones (most notable ones/ memorable ones) that drama fans feel NEED to be on all watchers list. Try not to list what others already have, just share your "best" k drama. What should I have seen?

It's easy to think that everyone should watch my personal favourites (lol), so I'll list them.

White Christmas - This is so short drama that it's easy to recommend to anyone. It may have not been a big hit at the time, and with international viewers it was a bit like a cult gem... But now that its cast is gaining popularity, this drama too is more relevant.
God's Gift - 14 Days - Jo Seung Woo does a drama! With Lee Bo Young! Awesome.
I Hear Your Voice - the sweetest romance around. And a great villain.
Unstoppable High Kick - iconic sitcom! Plus, it's one of those shows that gave a good kick to its young casts careers. Kim Bum and Jung Il Woo, anyone?

But really, I always have this feeling that I should be watching dramas that had those monstrous viewership ratings in Korea. Say, a top 50 list of all-time most watched dramas has these dramas from the past 10 years:

Jumong
Baker King Kim Tak Gu
My Name is Kim Sam Soon
Unexpected You
Famous Princesses
The Sons of Sol Pharmacy
Shining Inheritance
The Moon That Embraces The Sun

...I haven't seen them all. But like I said, I have this feeling that I really should.
These are my absolute favorites! :D
Reply 1997
The Master's Sun Bad Guys
I Hear Your Voice
Liar Game
The Three Musketeers
Two Weeks
My favorites:
My Love from Another Star
Coffee prince
Bridal Mask
Queen In Hyuns Man
Reply 1994
I third I Hear Your Voice and second White Christmas
Ugly Alert
Family's honor
Secret garden
Padam padam
New tales of gisaeng
Personal taste
Gu Am Heo Joon

I would say the some older k dramas that I think that many   k drama addicts have seen  
my girl 
autumn in my heart
goong 
full house
sorry I love you
stairway to heaven 
save the last dance for me



Healer - i know it's still ongoing but it's one of hell of drama
Gu Family Book - ignore the father story in the beginning and the rest is awesome :D
i fourth I Hear Your Voice
King2Hearts - don't let the name fool you ! It's one of le seung gimasterpieces !!
i second Liar Game
Pinocchio 
i second Reply 1997
The Heirs 
i second The Master's Sun
You're All Surrounded
Ok, so 2014 was a really bad year for me when it comes to dramas, so don't expect many of them. Here is my "must-watch" list!

1. Ojakgyo Brothers (if you ever feel like trying a family drama, then you must watch this one)
2. Wonderful Life (really heartwarming, a classic)
3. Liar Game (psychological)
4. Innocent Man (one of the best melodramas ever)
5. Iljimae (a must for every kdrama lover)
6. I Nee Romance (I always recommend this to everyone, one of my all time favorites)
7. I Hear Your Voice (the best 2013 drama for me)
8. Gu Family Book (really easy to follow and enjoyable, also a BIG hit in Korea)
9. Dal Ja's Spring (very popular in Korea)
10. Coffee Prince (one of the first "girl dressed as a boy" kind of drama, the chemistry between the leads is amazing as well)
11. Queen Seon Duk (the best drama of 2009)
12. Reply 1997 (you can consider this one a major trend)
13. Secret (loved this melo)
14. Shining Inheritance (the drama that made Lee Seung Gi the star he is today)
15. White Christmas (one of my favorites, a must-watch)
16. The Master's Sun (no comment, just perfect)
17. The Princess' Man (the best romantic historical drama for me, hands down)
18. What's Up Fox? (this is a hidden gem in dramaworld, but it's really beautiful)
19. The Greatest Love (a romcom that was loved by many)
20.Bad Guys (just give it a try)
My personal faves (w/o repeating other's recommendations) are:
(Tried to put them in some sort of a MUST WATCH order, but they're ALL great movies, did the best I could though.)
1. More than Blue
2. East of Eden
3. Love Rain
4. Night Watchman's Journal may be biased, I'm a Jung Ill Woo fan)
5. Family's Honor

I know you said not to repeat others suggestions, but I thought if several people recommend the same movie, it may be worth watching...right? 
1. Stairway to Heaven 
2. Moon that Embraces the Sun (may be biased, again I'm a Jung Ill Woo fan)
3. Heirs
4. Secret (may be biased, also a Jay Chou fan)
5. I Hear Your Voice (may be biased, also a Lee Jong Suk fan)
6. Bridal Mask
7. Master's Sun
8. Iljimae
9. Pinocchio (may be biased, again I'm a Lee Jong Suk fan)
8. Gu Family Book

Enjoy your movies :-)
Kdrama staples - Full House, My Girl, Secret Garden, Coffee Prince, You from Another Star (these are trendsetter dramas that every dramawatcher knows..)

Dramas that are something different - 
Nine Times Time Travel
White Christmas
Secret
Reply 1997 
Bad Guys

Other must-watch dramas I can vouch for even though I haven't watched them for one reason or the other, mainly lack of time. I NEED to watch them.

Liar Game
Bridal Mask
The Princess' Man
Master's Sun
I Hear Your Voice
God's Gift
It really depends on what your looking for. Here is my list of "classic" Korean dramas that everyone knows and everyone has watched. 

1. Coffee Prince
2. Secret Garden
3. City Hunter
4. Boys Over Flowers
5. Reply 1997
6. My Girlfriend is a Gumiho
7. Heartstrings
8. Your Beautiful
9. Full House
10. My Name is Kim Sam Soon

Personally I wouldn't bother with the last three because I didn't really enjoy them, but they are definitely considered a few of the best dramas out there.
If your just looking for personal favorites I definitely recommend these:

1. It's Okay, That's Love (the OST is AMAZING.)
2. Healer
3. Innocent Man (aka Nice Guy)
4. I Hear Your Voice
5. Queen In Hyun's Man
6. That Winter, The Wind Blows

And Here are some non-korean dramas you're sure to enjoy (in no specific order)

1. To the beautiful you (japanese one, not korean!)
2. Autumn's Concerto (Taiwan)
3. Boss and Me (Chinese)
4. Boku no Ita Jikan (Japanese. REALLY SAD)

So enjoy! You can also check this out, it's mydramalist's top dramas based on the sites ranking system by all fans.

http://mydramalist.com/browse/all?types[]=68&sort[]=top&countries[]=0



THE REAL LIST OF KDRAMAS EVERY SHOULD HAVE WATCHED AT LEAST ONCE : 

1. Queen Seon Deok ( simply the all time best drama , it will touch you in a way no other dramas can )
2. Empress Ki  ( almost as good as Queen Seon Deok )
3 . Boys over Flowers and City Hunter  ( two dramas starring Lee Min Ho that EVERY KDRAMA WATCHERS have watched ) 
4. King Of Baking Kim Tak Gu
5 Iljimae
6 The Princess' Man 
7 The Innocent Man 
8 Secret 
9 Shining inheritance 
10 The Greates Love
11. My girlfriend is a gumiho  (<333)
12 . Reply 1997 
13. Thank You ( SIMPLY THE MOST BEAUTIFUL DRAMA EVER AND THE MOST TOUCHING SERIOUSLY GIVE IT A TRY)
14 . Liar Game ( the Korean version )
15 . Jumong


I just saw that you gave a 10 to Empress Ki which is awesome and you're totally right  so Ireally recommend you Queen Seon Deok since it has a similar story but it's completely different at the same time  ( Strong Female Lead who cross-dress in the beginning , Love Triangle , Complots , rebellions , an AMAZING OST , Beautiful sceneraries and Costumes etc ... ) 
Some that haven't been mentioned:
Marriage, Not Dating
Bride of the Century
Sungkyunkwan Scandal
Rooftop Prince

Ones I second:
Liar Game
You're All Surrounded
Secret Garden
It's Okay, That's Love