ML starts out as self destructive, cruel, rude, arrogant, rebellious, irresponsible, a womanizer, manipulative, or something similar, but reforms.

At least one of the leads is an athlete (someone who regularly plays a sport at a competitive level) or an individual who was a talented athlete…

Dramas set in the 19th and early 20th centuries / Republican Era Chinese drama / etc.

Some have a broader military theme. Some don't. There's often a lot of saluting or strategizing. 

Medical dramas or dramas with a doctor, medical student, psychologist, or physical therapist main character.

The ML is by the FL's side. He supports her and knows her better than many boyfriends know their girlfriends, but his "title" is something…

Dramas that involve the police, detectives, criminal profilers, criminals, corruption, etc.

Two or more of the leads are connected to a tragic accident or crime that happened in the past and deeply affected them or caused both of them…

Romance Dramas where one lead has to stand in front of a target (or is otherwise close to the target) while the other lead shoots a gun or an…

They don't yell. They don't even speak that much. Some of them sometimes punch people or things. Loners or good listeners (or both). 

The ML gets frustrated with the FL for not getting jealous. He wants to feel her affection and possessiveness, but she's acting in an opposite…

Dramas where there'd still be a complete story if you took out the romance.

Sometimes its just a tease of the possibility of reconnecting. 

Dramas with intense chemistry, subtext, innuendo or queercoding between two female characters that doesn't build up to a canon queer relationship. Or…

One lead trains their love interest in something (not sports). 

In the broadest sense. These dramas have at least one scene where leaves fall and / or have changed colours.

One of the leads has a job that is very unusual, somewhat adult themed or slightly embarrassing from an immature mindset, or just jobs that…

Taiwanese dramas where (a) a second-generation mafia boss who loves their sister, (b) took over the organization after the previous boss was…

Recent dramas with good cinematography, a special feeling of softness, and varying degrees of melodrama that touch on trauma, loss, or separation.

The leads are adults dealing with adult problems. Not comedies, fantasy dramas or action dramas. There might be some crime but the drama is…

Dramas about adulthood without a big, dramatic sci-fi / crime / terminal illness / chaebol etc. factor, good cinematography, and an understated…