Both dramas are about a group of people who chase down bad people. Bad Guys is with criminals employed by the police, and Taxi Driver is with employees of a taxi company who are employed to take revenge on bad people. Both groups don't exactly use legal methods, and aren't afraid to be pretty violent against the bad people.

There are nine actors of Joy of Life that are also in My Heroic Husband, if you want to watch a similar cast.

Both based on a webtoon.
Both about school bullying.
Both short dramas.
In both dramas, the fighter(s) agree to protect a weaker character.

Both dramas have a romance façade, but are truly about societal and psychological issues. There's moral grayness all around.

The love triangle is prevalent in both.

Both dramas are heavy on political talks, with family drama. And they make it absolutely not boring. Both have great production values.

Both drama serve as the female lead's "dog."

Kono Otoko is more of a comedy while Kimi wa Petto is surprisingly grounded.

The two dramas are about undercover police work in the drug world. In both dramas a woman the main character loves gets killed and the main character goes undercover to find her murderer.

Both adapted from BL stories and not explicitly BL in tv format.

Both fantasy

Both have a dufus main character and a serious nerd other main character

The Untamed is gayer, but they're honestly both pretty gay