Superheroes aren't only about what they do - they're also about what they wear. Their costumes not only serve as a means to their crime-fighting but they also reflect their personalities. What a superhero sports says a lot about them as a person and as a hero.
The DCEU is full of darker stories that don't treat its heroes with kindness. The costumes reflect that because they make those who wear them look serious and grave. There are also those heroes who are much more colorful - and as a result, they also tend to be optimistic and open toward the future. Not everybody can pull off their costume, though, and some DCEU characters simply have better costumes than others.
Best: Superman
There are multiple things the DCEU could have done better in regards to Superman - but his costume isn't one of them. Although it differs from the comics, it still has enough recognizable elements to immediately identify Superman for who he is.
The colors are a bit more muted than in the comics, but then again, the DCEU Superman isn't as optimistic as his comic-book counterpart.
Worst: The Flash
It would make sense for the Flash to have a fancy suit since he works alongside Batman who has plenty of resources. But unlike his comic-book version or the one from the TV series, the DCEU's Flash doesn't look so great.
Perhaps it's because his costume doesn't fit together, there are parts protruding, and overall, the general aesthetics of the costume leave a lot to be desired. The best thing to being said about it is that it at least follows the Flash's typical color scheme.
Best: Wonder Woman
Just like Superman, Wonder Woman also has an established look that defines her - and lets her enemies know who they're dealing with as soon as Wonder Woman arrives on the scene.
It's true that her armor doesn't cover a significant portion of her body, but Amazons have a culture different from humans, and Wonder Woman's armor reflects that. Since she's as close to bulletproof as they come, she can afford to leave her arms bare and rely on her bracelets.
Worst: Cyborg
Technically, Cyborg's costume isn't a costume - it's his body. The problem with it is that it sometimes doesn't look as realistic as Cyborg would have deserved.
The audience is willing to suspend their disbelief, and seeing a man whose body is mostly made of metal isn't something they couldn't accept - if only it wasn't obvious at times that Cyborg's body is mostly CGI.
Best: Shazam
Shazam's costume is colorful, over the top, and with just the slightest trace of a mythological look - because Shazam's powers have, in fact, a magical origin, and he is colorful and over the top. Shazam is a kid, and not just at heart, and his costume in the DCEU reflects that well.
The fact that Shazam's costume mirrors his character becomes even more obvious when the audience compares Shazam and some other, more serious superheroes who have darker costumes such as Batman, or even Superman in this universe.
Worst: Harley Quinn (In Suicide Squad)
Harley Quinn wears a special set of clothing when she goes on the missions alongside the Suicide Squad. But her outfit offers very little protection. It's very Harley, meaning it's colorful and crazy, with a lot of elaborate details - but the extremely short shorts don't do Harley much favor when it comes to protecting herself from injuries.
In the subsequent movies, Harley switched her outfit for a longer one, but she still wears her hair in her signature two side ponytails.
Best: Wonder Woman (Golden Armor)
Not everybody can pull off golden armor but it looks like Wonder Woman and her Golden Eagle armor that also appeared in the comics will be an exception to this rule.
Wonder Woman wears this armor in her new solo film Wonder Woman 1984, and while most of the fans have yet to see it in action, it looks amazing in the promo materials so far.
Worst: The Birds of Prey
The biggest flaw of this superhero team's costumes is that they aren't very memorable. They're mostly clothes anybody could find in their wardrobe, with a few notable exceptions like Black Canary's belt.
To be fair to the team, they just barely got together at this point and they haven't yet had the time to figure out their superhero outfits. It doesn't help their case that Harley is just as colorful as always and draws most of the audience's attention to herself.
Best: Aquaman
The King of the Atlantis can't look like a human, and Aquaman's armor does an excellent job of reminding everyone of that fact. In historical times, kings often wore golden accessories to remind everybody of their status, so this is fitting.
Arthur took this to a whole new level with a shiny armor that covers his body like a shield. Combine it with the trident, and the overall effect is more than just memorable.
Worst: Enchantress
Enchantress has the same problem that Cyborg does. Her costume is fine, it fits the type of character she is - and she's a powerful sorceress who doesn't care if she'll frighten people.
The issue is that Enchantress once again looks like a CGI character too many times, and it disrupts the flow of the film since it draws attention to itself. Some scenes make it more obvious, like the one in the picture above.