-Both are kind of unhinged investigative dramas with a rebel ML and a grounded FL.
-The male leads both use unusual tactics to solve crimes. Jin Yi Soo (Flex X Cop) uses his chaebol connections and money to get insider information about cases. Jin Jung (Bad Prosecutor) uses his craziness.
-Both have well-choreographed fight scenes and good direction
-Dramas are case-centric and focus mostly on the investigations, but the main characters all have personal traumas/storylines to work through
-Romantic undertones between the leads. FXC hasn't finished airing, but it has more romantic scenes than BP
-Both casts have great chemistry
-They're fun dramas to watch when you need a taste breaker from fluffy romances

Both have a somewhat similar vibe, even though MTF isn't music-related, because the leads' romances are kind of similar. In both, the leads go in circles throughout the series. Both relationships spend the series circling an issue that continually threatens/makes them question the relationship. Also, the FLs are similar in that they're both are struggling to start their careers in their respective fields.

Both shows feature an idol group that works to their debut by going through missions and performance evaluations with the threat of member eliminations if they fail. In both shows, the groups work hard to debut with all their respective members.

Road to Kingdom is a survival music competition that features Pentagon as one of the contestants. Pentagon has some amazing performances on RTK, and it's fun to watch.

LwF is a kdrama so its storyline can get a little darker than PL, but it also deals with various mental health issues in a realistic way.
Both involve childhood incidents that cause eventual misunderstandings with repercussions. In LwF, the leads become obsessed with looks, in different ways; and in PL, the FL gets a strange illness.
LwF's characters are a little zany and over the top, but it's an entertaining watch.

-Both are fluffy dramas that are easy to watch and super sweet
-Both FLs have an issue that only the MLs can solve that stems from a shared childhood trauma
-Both are really cute, if you don't think too hard about the mechanics of LTWYA's concept
-The FL in Poisoned Love is actually in LTWYA, and her character's storyline is my favorite in the show. If anything, watch it for her.

In both, the bubbly/optimistic FL changes the ML's seemingly cold personality. MYEM is slightly darker and less romanticized, but it does have sweet moments that sometimes reminded me of ALSB.