I think the idea of a recurring villain is interesting, but I'm not sure it's necessary. I probably would've rather had Logan be the "recurring sliding villain" since she's a flip side on our main character. I think there's also an argument to be made that maybe you replace the "which Arturo slid?" story with a Quinn double that can't complete sliding on his own and steals Quinn's place. Then you have a villain inside the group, and the person "chasing" them is our original Quinn.
This might be too mystical, but I'm thinking based on what ireactions and DMD said about a villain that can somehow "slide" their consciousness from place to place into a new double. Maybe they interact with a villainous Bennish on a world, and they leave him behind. But then in future episodes, they keep running into doubles of Bennish on each new world. And like ireactions said, each time they run into him, he seems more of a threat. And it turns out it was the villainous Bennish each time. Maybe each time he enters a double, he gets more control, and by the end of the arc/season, he can finally do whatever he wants. Or maybe he has full control each time but is playing the long game.
Sorta like Sliders meets Quantum Leap.