King would be my default answer and the easiest route to go so I'm leaning towards this the most ^^
Denjiro being nowhere tbf atm is pretty odd tho, considering he's been one of the most highlighted of the scabbards, I can't help but wonder what Oda has in store for us with regards to him. So who knows a Zoro v Denjiro fight might be on the cards, I can't imagine Oda is saving Denjiro to slay Orochi's last head so maybe he gets manipulated by Orochi in some way

As weak as Orochi is, he's a mythical zoan user so who knows what else he has under his sleeves ^^
Also I think Oda is gonna have Momo more involved with the Kaido plot so if Momo doesn't kill Orochi then Zoro would be the next person I'd favor to do it ^^
Though, Zoro having to make his way around the castle to find Orochi significantly reduces the chances of a matchup against Orochi and Denjiro

so maybe Orochi makes his way to the live floor to make tings easier lol