If we consider the protagonists, Hinata has a sharper personality and actively uses unusual gadgets and props in his game, and he also has his past as Izuru Kamakura to provide more potential, plus his glowing white form from the endgame. There's also Monomi that could be worked into his moveset considering his closeness with Nanami. His game also has more minigames to work with, such as logic dive or the contradiction swordfight.
Komaru is actively from an action game in UDG, and has her megaphone that's used to stun the Monokuma bots, plus Fukawa/Jack could easily be part of her moveset as well, giving us a fan favorite to boot.
Kaede is a pianist which can give her a music-themed aesthetic to help her stand out, and she again has a stronger personality than Naegi with her more sarcastic and easily-worked-up nature. Plus, as much as it breaks my heart, the fact that she's the culprit in chapter one alone gives her even more potential with her improvised Rube Goldberg-esque failed murder machine. Shotputs galore.
Shuichi is a detective, giving him a more methodical style, and again he's unique due to the new minigames, the liar bullets, and his entire endgame that causes him to do what no other character in the series does by actively rejecting the very mechanics that are trapping him in the game. His entire playstyle could be focused around detection and misdirection.
And moving on from the protagonists...
Junko is the big bad of the series. It's to the point that her very existence is parodied by V3 because "it's always Junko". She's absolutely bursting with personality that can change at a drop of a hat, creating an unpredictable character that could use any of the Punishments from the games as mechanics, her cell phone and reality warping powers from the second game, the Warriors of Light from DRAE, or even Tsumugi's cosplays from V3 if they wanted to go with a Snake-esque amalgamation.
Komaeda is one of the most popular fan favorites in the series and his entire gimmick is being the luckiest person in the world that's then followed up by extreme bouts of bad luck. He's a Remnant of Despair who has felled nations so we know that he can survive anything outside of what he himself sets up and a playstyle focused around actively putting yourself at a disadvantage in order to gain massive advantages is just crazy interesting to think about, especially when you start going into famous scenes like Russian Roulette.
And finally, of course...
Monokuma! The mascot and the thing that ties every single game together! Brimming with personality? Check. Weapons, comical buff forms, demented Looney Tunes contraptions? Check. References to the brutal punishments in the games? Check. Recognizable and iconic? Check! Between the Monokuma units, the Monokubs, the various goofy gags and forms he has, and the fact that he isn't a walking spoiler like Junko, you have a pretty compelling case to pick him over any other DR rep.