I used to think Saka was our most important player but since last season it's clearly been Rice imo. Saliba was out, Gabriel was out, Saka and Martin were missing more minutes than they played, and we still won the league with Declan heroballing week in and week out. If he'd done that at Bayern or Barca he'd be odds on for the ballon d'Or right now.
If we ever want to win a CL final we definitely need Saka fit though. He's by far the best player we have, and unless Vinicius has a change of heart I don't see who we'd sign who could change that.