I'm borrowing criteria I used to explain my favorites at the 2007 Anchorage International Film Festival, and I'll use those here to help explain the case for Hidden Figures.
So what were my criteria? There are several factors.
1. Technical Quality - There's a rough continuum from
shaky...........no problems.............very good...............innovative.
You can see this is not exactly a continuum. Innovative is good when it works, but not when it doesn't. The technical stuff, ideally, works so well it enhances rather than distracts from the story.
2. Content - There's a vague continuum from:
Negative/disrespectful ............Boring.........good story.........original.......current.........important
Again, as I look at the line above, this is more a list of factors to consider than a continuum.
3. Use of Medium. Movies combine sight and sound and movement and timing. The best movies are those that take advantage of the medium and tell their stories in ways that you couldn't tell it orally, in a book, etc.
4. Whole Package. Even with weaknesses here and there, a film could pull it off by doing some things so well that the problems don't really matter.
Applying the criteria
As I mentally compared La La Land and Hidden Figures, it's clear that Content became my most important category.
La La Land scores high on Use of the Medium. My brief review of it after I saw it mentioned that the camera was one of the actors in the film. It wove in and out of scenes like another person on the set. It wouldn't have worked as a book, you have to see it to get the effect. I walked out of the theater happy. But eventually, I realized that the whole movie was like a bubble - beautiful and shimmering and . . . empty and ephemeral. There was no real content, the singing and dancing were acceptable. Like a bubble, after it popped there was nothing left. (Well, if you had just been through a similar kind of disrupted relationship it might feel more meaningful, but it didn't really tell us all that much about that either.)
Hidden Figures on the other hand was rich in Content. It was a great story that not only told about the lives of the three main characters, but their place in a pretty much unknown part of American history. It smashed so many stereotypes about blacks, about women, about the US space program that it's impact is huge.
The three women were part of the 'colored women calculators' at NASA. Their job was to do the math before computers were installed. Despite American stereotypes, they were all three extremely bright mathematicians. The film helps demonstrate why women aren't considered good at math and science. The movie is replete with ways their brains were used, but they were kept invisible while the men got the credit for their work. It also powerfully shows the obstacles that black women faced in the Jim Crow South. Most vivid was Katherine's regular run nearly a mile each way to get to the only colored women's room on the NASA campus - in the heels that women were required to wear. She was assumed to be the janitor when she walked in, and someone puts up a colored coffee pot so she won't contaminate the white folks' coffee. And given the level of racial conflict in the US today, being reminded of sanctioned racism in place in the 60s. And it's important to see real historical role models of smart, resourceful, black women and to be reminded (for some it will be the first introduction) that black women can be, were, and are brilliant mathematicians and scientists if they're allowed to be.
Technical Quality and Use of the Medium were high, moving the story along without being flashy or in any other ways calling attention away from the story.
Fences and Moonlight are also good films with important stories about black lives. The language in Fences is exquisite. The story in Moonlight is compelling, but the structure is sometimes hard to follow. That's not necessarily a bad thing. Any good work of art reveals itself more and more with each new encounter. I could learn a lot by seeing Moonlight a few more times.
Ultimately though, the characters portrayed in Fences and Moonlight are African-American characters we've seen on screen over and over again, though usually not in such a rich and understanding way.
But the characters in Hidden Figures are ones we have never seen portrayed on screen before - brilliant, gutsy black women who are vital to the US Apollo program, not because of their unsung physical labor, but because of their brains and insight. This is a movie that corrects a huge oversight in the narrative of African-Americans in the space race, and by extension probably in a lot more areas that we don't know about.
Thus the content of this compelling story starts to fill a huge gap in our knowledge of how African-American women contributed to the United States, and thus to our understanding of the huge loss we've suffered by not fully using the talent of ethnic minorities and women as we strive for a better, stronger USA and world. Ultimately, Hidden Figures just tells the best story and the story we know the least. Thus, for me, it's the movie that matters the most.