Riddick gets feats in order from Escape from Butcher Bay, Assault on Dark Athena, Pitch Black, Dark Fury, Chronicles of Riddick, then Riddick. The 2 video games act as direct prequels to Pitch Black.
He kills a few Bioraptors in Pitch Black, a ton of Necromongers in Chronicles, and tames his dog in Riddick before taking down dozens of Mudcrawlers, who only gave him trouble when he was surrounded by them on a mountaintop and weaponless. The first one he went against to escape the cave was an easy kill after he tested it to figure out everything it could do. He even let it sting him to trick it since he had made himself and the dog immune by repeated venom injections. Then after getting sent flying and cracking his head against a rock by another one, he immediately kills that one too.
Also keep in mind that Riddick is stealth personified, and is probably better at it than the Moorwen, and he can see the Moorwen glowing in the dark, so it's hunting mechanism will be used against it and it can never sneak up on him. All he needs is a weapon capable of cutting it.
He's also killed those weird jellyfish creatures in Dark Fury. Riddick is pretty tough, and combining all his movies and such I think gives him a majority.
Two really good arguments for and against a Riddick majority.
I myself recently brought up Riddick’s out of movie experiences being canon when he was pitted against Prince Nuada, so yeah, i have to agree on Riddick majority here, but not a huge one; The Moorwen’s tougher than any single creature Riddick’s faced imo.