What are your personal headcanon of kiyomi takada?
I... don't really have any, but what I do have is an interesting bit of cultural context that might put her personality in a new light:
The news are a notoriously difficult field for women in Japan. It's a field that is extremely male-dominated and absolutely rife with sexual harassment that is entirely normalized, even today. (x)
The job Takada specifically holds is that of a TV Announcer. It is another field with incredible gender inequality.
Near is looking at a ranking of 'female announcers' here and it absolutely has to be noted that it's not a ranking of 'announcers who happen to be female' but of 'Female Announcers' as an almost separate job category. The Japense wikipedia page for announcers has a whole subsection about female announcers.
They are basically treated as idols - hired from top universities but primarily for their looks, and designated as eye candy for the viewers. The sexual harassment they face is likewise immense and they are often forced to retire in their mid-20s as they stop being of the 'desirable' age.
The TV station NHK which Death Note's NHN is a based on is more serious about it, at least - their female announcers are trained well and selected for the quality of their work, women in their 30s can also be announcers for NHK - so Takada did score the most serious 'female announcer' job that she could, but it is obviously a profession with a lot of prejudice speaking against it.
We see this reflected in the series by Near who immediately dismisses her abilities based on her gender and age, seeing her as just another of those 'basically pop star' announcers.
Which is notably different from how Mikami, who has very high standards, describes her work:
Takada is a woman who has chosen a career in an excessively hostile field because she is dedicated to social issues and reporting. She's evidently passionate about politics and social ills and putting her all into her job. She's a go-getter who traverses difficulties because of her strong conviction and own drive to get ahead.
(Now, I concede that Ohba probably wrote her with female announcer stereotypes well in mind, uncritically, but I think the character he came up with still reads as exceptionally strong-willed and ready to carve her place out in a world that does not take her seriously by default.
Frankly, the way the narrative makes fun of her for being stuck between distaste and smugness at being seen for her appearance is sick, considering society ingrains it in women that they should want to be desirable first and foremost. Of course she has conflicted feelings about a) being seen as a Good Pretty Woman vs b) wanting to be taken seriously as a professional and just as a person.
Her dislike stat of 'stupid women' also reflects that - she has the internalized misogyny of somebody who wants to surpass the rigid gendered expectations she was raised into and that she never felt fit her - but who has not yet realized that those are not the fault of other women for 'not being emancipated enough'.
It's such a common expression of wanting to be More than society allows but feeling like the only way to do this is to be Not Like Other Girls.)