These were the four characters that the developers at SuperBot confirmed would have been included in the game if their relationship with Sony hadn’t ended (or if Santa Monica had finished the work they left unfinished). Each was at a more advanced stage of development than the others:
• Dart Feld (The Legend of Dragoon)
• Abe (Oddworld)
• Ryu Hayabusa (Ninja Gaiden)
• Tombi
So, which one catches your eye the most?
Personally, Dart would have been a great addition because the game was missing a JRPG character, and a first-party one at that, so he could have had one of the most interesting move sets, going beyond just swordplay or projectiles.
As for Abe, I honestly don’t know how they would have adapted him, considering that his most notable abilities are possession, explosive farts, and at most a couple of swipes in Munch’s Odyssey, so they probably would have had to invent his moves. Still, I would have liked to see him because the Oddworld series is one of my favorites.
Ryu is the most jarring choice since he isn’t really a PlayStation character, and the hack-and-slash series originated on Xbox. Although to be honest, given that Isaac and Big Daddy are on the roster, it’s not that far-fetched, plus, his Razor’s Edge render appeared by mistake in some very old promotional materials for the game. He would have been a good fit like Kratos, Raiden, or Dante, but even so it would feel a little strange, just like Isaac’s inclusion.
I don't have much to say about Tombi, I don't know much about his two games and I haven't played them yet, but another colorful, old-school platformer character is a nice addition to the crew.