King vs Zoro:they both have swords. Thats basicaly the only good argument.
King vs Sanji.:
They both have abilities based on fire attacks.
They both have a version of dj.
They both fly.
They already clashed.
King aparently wants to kill Sanji. He wanted to break him in half like time when they clashed.
And people wonder why someone would think about a potential match between Sanji and King.