I won't be counting the leaked characters.
We need diversity, we already have a bunch of gun wielding characters, so characters like Stryker should sit this one out.
The game also lacks 3d characters so we need more of those.
My opinion:
Kenshi: The game already lacks a pure swordsman in the game, as well as a telekinesis user, Kenshi fits both roles perfectly.
In a game full of Ninjas, a Samurai is always a breath of fresh air
His gear should be His blind fold, Sento, and the third piece could be either another Sword or his warrior spirit that he summons in his possessed variations.
Havik: his ability should allow him to use moves that are absolutely unique and it's impossible to go wrong with him, and his chaotic nature should allow for some interesting character banter.
He's pretty much the closest thing to Deadpool we can get, unless they bring Deathstroke..
Gear would be his morning star, his helmet, and something else, maybe a kamidougo?
Hotaru: One of the most underrated 3d characters, having Havik without Hotaru is insane, they both have a nice duallity going on.
Lava bending is cool and all, but I would love if they could retcon him to being Light element user, if any character would have light powers, it would be him.
Gear would be his Naganita, flags, and maybe a helmet or another weapon.
I would say Tremor and Rain/Hydro but Cetrion stole most of what made them unique...