99% sure King will have in the end, overall, a greater lore. He was the main villain of WCU, he estavlished a relationship with Luffy, Oda could even make him reappear like Croco or Lucci while King on thevother hand is just at best the 3rd villain of this arc and will just be the rival of Zoro in Wano, maybe even not the main rival since Zoro fought Kaido and BM. So overall their powerlevel should be very close but Kata's role in the end makes him more important for the story. At least if Oda doesn't build some super duper important stuff beeded to find the OP upon his race or something like that (but we know it will not happen).