For me. my top 5 recommended kdrama. my life changers. are those below list

1. Itaewon Class 

2. because this is my first life

3. Vagabond

4. memories of alhambra

5.  Kill me heal me

What do you all think? To me this are my life changers

1. The Glory

2. Be Melodramatic

3. Eulachacha Waikiki

4. My Mister

5. Prison Playbook

  1. Healer
  2. Descendants of the Sun
  3. Twenty-Five, Twenty-One
  4. Pinocchio
  5. Goblin

But even with these, I'd have to obviously confirm with a person what sort of things they're into first.

Hmm...

Navillera

Missing: The Other Side or The Guest (not sure between these two)

The Penthouse

Under the Queen's Umbrella

Kingdom

1- My Mister 

2- It’s okay to not be okay

3- The Glory

4- Be melodramatic

5- My Name 

I tend to prefer the older ones to the newer...

Autumn Tale (2000)

First Love (1996)

Glass Slippers (2002)

I'm Sorry, I Love You (2004)

Stairway to Heaven (2003)

KOREAN

1) Because this is my first life

2) Ugly Alert

3)  Be Melodramatic

4) My Mister

5) My Liberation Notes

6)  Avengers Social Club

CHINESE

1) Meet Yourself

2) My Fated Boy

I have to add It's Okay That's Love to my list. INCREDIBLE.

The Heirs - Lee Min Ho started my KDramas addiction

Reply 1988 - Love the family, friends and food

Mr. Sunshine

Hospital Playlist 

Lovely Runner - my favorite current drama 

1. Exhuma

2. Lovely Runner

3. Mr Sunshine

4. Midnight Photo Studio

5. Moon Lovers

Some of my favorite Korean dramas that I highly recommend -

1. Reply 1988 - watch it for family and friendship

2. Descendants of the Sun - the ultimate love story

3. Youth of May - to cherish your love and loss

4. Healer - must-watch for action lovers & Ji Chang Wook

5. Twenty Five Twenty One -  youth, dreams, and bonds that shape our life

1- Sweet Home

2- Strong Underdog

3- Money Heist part 1 & 2

4- Just Between Lovers

5- Crash Landing on You

I will try to suggest 5 alternative titles to the multitude of gems you have already posted, they are among my favourites, even if they may not attract much attention

Ruler Of Your Own World (2002)

Sad Love Story (2005)

Lucifer/The Devil (2007)

The Spring Day Of My Life (2014)

Love Affairs In The Afternoon (2019)

in my personal opinion these dramas are perfect examples of great screenwriting combined with outstanding acting performances by the entire cast in each of them

  1. My Mister: Perfect slice of life
  2. Call it love: What can I say? Healing can sometimes come from your worst enemy.
  3. Lost: The last dialogue between the main couple is worth many rewatches where they each share about their affair just cause they only have each other to share it with.
  4. Mouse: That damned second half. I felt as if the land under me was being snatched away little by little and before you realize you are drowned in quicksand
  5. Have to mention 3 dramas here that depict the power of motherhood. Mother/Lie after Lie/Hi Bye, Mama!
  1. Mr. Queen (This is a historical and comedy K-drama. Plus, I love the female lead, and she plays her role  well.)
  2. A Time Called You  (If you enjoy time-travel K-dramas, this one's perfect for you. I watched it breathlessly until the end.)
  3. The Light in Your Eyes (By the end of this K-drama, you realize that your youth was the best time of your life. If you're looking for a K-drama with surprises, I highly recommend it.)
  4. Summer Strike (Sometimes, the monotonous life we live makes us forget how simple things can bring us joy. As you watch this K-drama, you'll slowly feel a sense of peace filling you.)
  5. Goblin (It's that well-known K-drama from 2016(the best year for K-dramas). Even though everyone knows it, I still recommend it. It never gets old.)