I think the CO didn't really start to put their plans into motion until week 4. X sacrificed Whit, but without the CO i think Christian still puts her up but X maybe would have went a tad bit harder to save her. Not sure what the result would be but that week would be where we'd see the trajectory change (compared to what actually happened).
Tiff at one point had nobody gunning for her, and multiple allies/alliances (some were bs but still) who were willing to protect her. She had DX, and Christian who were winning comps left & right. Probably would still have X (maybe even Ky), and the Royal Flush probably would've been what the CO is now, but with non AA people in it.
So i'd say hypothetically Tiff would've been the most successful (followed by X). She 100% no discussion had the best path to the end. Out of everyone in the CO she's had the most to sacrifice, and has sacrificed her game (and her path to the end) the most. It's like DF & Azah had a chance at a contested 3 point shot. Ky had an open 3, X had a mid ranged shot, and Tiff had an easy layup she could've taken but decided to go for the contested 3 instead.
The CO were each assigned a person to steer away from targeting the alliance. Tiff arguably had more sway over DX, and Christian than X, and Hannah did. On top of that her person was Claire. Tiff (at least the first half of the game) had all her bases covered because she was that good socially, and at navigating through the game as someone everyone wanted to keep, and share information with. There was a point everyone were spilling their game to Tiff. And she was practically calling the shots.