Recommendations

=> The two dramas show the beginning (6 Flying Dragons) and end of the Joseon Dynasty (Mr Sunshine)
=> There is the impossible romance of the leads of both dramas due to them having different statuses.
=> The main cast has a group of 5-6 people. They are different from each other (some are born in high status, some low) but what they have in common is they are strong characters and stick to their principles
=> Both feature some martial artists as among the 5 or 6 main characters but none of them are the top male leads (Lee Bang Ji and Muhyul in 6 Flying Dragons vs Gu Dong Mae of Mr Sunshine)
=> Fans of Byun Yo Han from Mr Sunshine are especially recommended to watch 6 Flying Dragons, you will be surprised at how he's good in martial arts which he unfortunately didn't get to show in Mr Sunshine.

=> Both Hyun Bin dramas that are romance comedies where he has sizzling romance with the female leads
=> Hyun Bin's parents want him to marry someone else in both dramas
=> The female lead actresses in both dramas are two of the most successful actresses in Kdramaland , both having won Baeksang awards in both dramas and films, so good acting is indeed guaranteed in both shows
=> Both dramas were extremely popular after airing, to the point where Hyun Bin was shipped so hard to both female leads immediately after both dramas aired
Interesting Trivia about the two female leads connected to the two dramas:
1. Ha Ji Won (Secret Garden female lead) also played a North Korean person in love with a South Korean like Hyun Bin, in her drama King 2 Hearts
2. Son Ye Jin has a cameo in the last episode of Secret Garden

Both dramas are basically a time loop between two parallel timelines. The events of Leap Day led to the FL traveling to the timeline in 940920. Her actions in 940920 helped create the backstory of YKC in Leap Day. Which in turn saved her life in Leap Day and led to her ending up in the parallel timeline in 940920. It's complicated lol

=> A romance feauturing a special forces captain and a woman with her own accomplishments in her chosen profession.
=> First episode shows male lead fighting another soldier
=> Also features a second couple (the romances of the second couples have a bit more pain than the leads)
=>The second female lead and male lead are not in love with each other, but their parents want them to marry each other
=> Male lead often protects the female lead
=> Both male leads have their own team of soldiers. This is natural since both male leads are captains. Some of the people on these teams got close to the female lead.
=> Some parts of both dramas are set shot outside the Korean peninsula which gives a lot of beautiful scenery shots (Greece representing fictional country of Uruk for DOTS vs Switzerland for CLOY).
=> Both dramas feature North Korea (this is obvious for CLOY, but the male lead in DOTS also did have some missions in North Korea)
=> Both dramas are big hits and extremely popular when aired
Interesting Trivia (please don't hate me for adding this, I don't mean any harm):
=> The lead couples in both dramas are (or at least was in DOTS) both real couples that got married . (DOTS couple did divorce, hope the same won't happen to CLOY couple)
=> Female lead in DOTS and male lead in CLOY dated each other many years ago, their drama in 2008 is called World's Within

Queendom 2 (2022) is a sequel to Queendom (2019) and follows the same format featuring girl groups and pitting them against each other for the spot of #1 K-pop girl group.

Both dramas deal with characters with terminal illness and tragic love. Both of the characters lied to their lovers to hide their illness.

The FL in My Girl has the mental/memory issues.
The love interest in both meet the lead characters through work and learn about their issues from there.
In My Girl the ML helped the FL out of a feeling of guilt, but there are other complexities involving other characters.
In Don't Forget I Love You it only focused on the ML living his daily life with his memory issues, and we don’t see much progress with his cure.
But in My Girl we can see some progression and other aspects of her life besides her memory issues which was nice.
My Girl also has some drama angst with love triangles too.

In both the ML suffer from memory issues.
In both we see the FL help the ML with their memories.
In Well Dominated Love there is some history between the couple already, which is one of the main differences.
Similar vibes where the ML believes in love with the FL and works hard for it despite his memory issues.

A male person with an OCD falls in love with a female person, who might be a lot messier. The male in both is the boss of the female lead.

Both are cutesy romances between a boss (male) and his employee (a female). Both have this two people's cohabitating out of convenience... The boss seems a bit cold in two first episodes and so much as the story unfolds.

A girl befriends a person, whom she mistakenly take as a gay. She lets him in her house and expresses in front of him her most messy behaviour. However.. they fall in love with each other.

A girl falls in love with a person with a psychological problem, caused by somebody's suicide, who happens to be her boss.

Both are related to film direction dream. In "like in the movies" series they both become friends and are both interested in making films. In theory of love, same both the main leads are interested in making films. Both series are romantic and there is a character development.

A misunderstanding incident brought two together. This drama was 100% recommended if you love cute, sweet, and touching stories. Starting from acquaintances to lovers.

Sad and touching stories. But HE
Both dramas are similar in one fell in love at first sight. The other realized their own feelings after contacting one for a period of time.