Cyborg is IMO, one of the best minority characters in comics. He doesn't suffer from the same pitfalls many other minority heroes suffer from.
Great things about Cyborg that make him not just a great minority character, but also a great character:
1. Cyborg doesn't have the word "Black" in his name like so many other Black superheroes. There are many great characters who have a stigma attached to them because their names are clearly based on their race. Black Lightning, Black Goliath, Black Samson, Black Hood II, Black Eagle, Black Racer, Black Spider, Blackwing, and The Black Musketeers. Seriously, do we really need the word "Black" in every Black hero's name. We can't tell that they're Black just by looking at them? Who in the list above, would anyone call their favorite hero? None of them. Even the super-cool Black Lightning is held back by his name. Cyborg doesn't have this problem.
2. Cyborg is not a sidekick or a legacy character. Another problem with many Black heroes is that they will always be in the shadow of a White counterpart because they came second and because they are unoriginal. These characters boost diversity, but don't be mistaken, that's all they are really for--to give white heroes a cool, hip Black friend. These characters won't ever be THE main character of their own movie or cartoon franchise. The Falcon is Captain America's sidekick. John Stewart is slipping back into becoming Hal Jordan's sidekick. War Machine is Iron Man's sidekick. Goliath was Hank Pym's sidekick. Lothar is Mandrake the Magician's sidekick. Cyborg is not--and never has been--anyone's sidekick.
The problem with minority legacy character's like The Atom, James Rhodes, and Blue Beetle is that the fans of their predecessors will always push for the return of the first hero. Cyborg is the first of his kind, and he isn't trying to be anyone but himself.
3. Cyborg has history and name recognition. A huge problem with many minority heroes is that they are not easily marketable because people tend to only spend money on heroes with names they already recognize. No one read The Web or The Shield because they didn't have name recognition. People didn't want to spend $3.99 on heroes they know nothing about. Everyone knows who Cyborg is. He's a classic Teen Titan, and he was featured on the Teen Titans cartoon. While his miniseries wasn't a runaway success (for reasons I will address below), he is definitely a marketable property.
4. Cyborg has no criminal history. Iron Man is a m/billionaire. Thor is a doctor. Daredevil is a lawyer. Luke Cage was a jailbird. The Falcon was a street-hustler who had to be brainwashed to become a superhero. What kind of message does this send to our youth--black or otherwise? Cyborg has always been smart, athletic, and heroic. And he's never been to jail.
5. Cyborg doesn't have electric powers. There are already enough Black heroes with lightning powers, thank you. Storm, Black Lightning, Static, and Volt come to mind. Cyborg doesn't have the same old powers as everyone else.
Now, with all these things going for him, why is Cyborg not as popular or beloved as Green Arrow, Black Canary, Power Girl, Alan Scott, or Dick Grayson? Why don't you expect to see Cyborg on an Alex Ross cover?
What can be done to make Cyborg more popular and well-liked:
1. Give Cyborg a cooler costume and make his face look completely human. Probably the biggest reason Cyborg isn't more popular is his costume. Even his fans complain that it's too garrish and outdated. Why does he have a metallic wifebeater? Why are parts of his thighs and biceps exposed?
Another problem with his costume is that it's confusing. Can he take it off or is he just naked all the time? If Cyborg is ever to gain real success, he needs to get a cooler costume. One that looks like it can be taken off. One that doesn't look so 70s. One that doesn't expose awkward areas of his body.
And here's the thing that may be holding him back the most--the half face. Yes, Cyborg is supposed to be the Teen Titan version of The Thing, but there are two problems with that. One, no one calls The Thing their favorite character. Yes, he's likable, and people may call him ONE of their favorites, but at the end of the day, he looks like a freak. And Two, Cyborg can have the recurring Thing-self-loathing storyline without looking like a freak. He's a cyborg now, which means he had to give up his life's passion--Sports. On top of that, even with a completely human face, he not completely human. He's a cyborg.
Cyborg's image issue draws attention to the fact that he's a Marvel character is the DC universe. People like DC heroes because they are ideal. We want to be them. We want to fly like Superman and be as intelligent as Batman. But who honestly wants to be Cyborg? No one. He looks weird.
2. Upgrade Cyborg's powers. Yes,there a plenty of minority heroes in DC with medium level powers and no powers such as Mr. Terrific and Vixen, but there a few Black heroes who seem like they could ever keep up with Green Lantern or Wonder Woman. Yes, there's Black Lightning and Icon, but the former will always be held back by his name and the latter will always be held back by his origin, personality, and costume.
Instead of making Cyborg an Iron Man level hero, make him a Magneto or Green Lantern level hero.
While the clip above is about The Flash, it shows us that tech heroes can be immensely powerful also.
What should Cyborg power's be? Here's a list: *EDIT* NOTES ADDED
1. Give him at least Aquaman level (100 ton) strength, but preferably make him as strong as Wonder Woman.
2. Replace his Sonic Cannon with an energy based cannon. In video games and cartoons it already looks like energy anyway.
Or give him a cannon with multiple effects (sonic, energy, etc.)
3. Give him technopathy--the control of machines. Cyborg should be like a good version of Sky-net. (Forget this. Oracle still needs a job)
4. Boost his invulnerability to Aquaman levels, and allow him to regerate by using the metal around him.
5. Allow him to assimilate the machinary around him like War Machine used to be able to do.
6. And maybe give him some "liquid metal" features like the T-1000 or T-X. (Forget this. It's a little much.)
If you're wondering how he should get his upgrade, just make him get sucked into his father's multi-dimensional portal (you know, the one in his origin) and have him come out mysteriously better than before. Bam!--we already have a new Cyborg storyline. It's not hard.
3. Give him a girlfriend. Let's see another side to his personality. We already know he's a good friend, leader, and mentor, but we haven't seen him with a woman yet. No Bumblebee doesn't count because they haven't gone out in the comics. After he's gotten a full-face, let him date Sara Simms or Starfire.