Yall are completely wrong. The answer isn’t Sanji or Nami, saying either of those two is like airballing a free throw shot with no one near you. The answer is Robin and imma try to keep it brief.
Valuable Skills: For one she can read the poneglyphs (way more valuable than anything Nami and Sanji can do) and without her, the rubber boy won’t be Pirate King, the crew wouldn’t go to Raftel and Nami won’t be able to draw that map to get to Raftel. She also spits the most useful facts and information when the crew needs it, Sanji meanwhile spends half his time uttering gag lines and Nami is ok when it comes to interactions, but she is no where near as knowledgeable as her
superior, Robin.
Dream: Has the more impactful dream than Sanji and Nami. This shit not even close tbh. Her dream of learning the true history is tied with the entire overlying narrative of the series and its history, and as a result brings about the very final war. That is simply more significant than finding an exotic sea or whatever in the world Nami’s dream was about, if I can’t remember it off the top of my head, that goes to show how little value it has to begin with.
Impact in the Verse: Dubbed as the “Light Of The Revolution” by the Revolutionaries, the main opposing force of the WG. Also the only member of the crew besides Luffy to be formally recognized by the most dangerous man in the world:
the same cannot be said for Sanji and Nami. Sanji hasnt even been able to excel in his role as the fighter, which is why it makes sense he has turned to what he does best; cooking.
But doing things like baking a cake that only momentarily distracted Big Mama isn’t no where near being recognized as the crucial piece to overcoming the 800 year tyrannical rule that is the World Government. I mean what is Sanji going to do that time? Prepare some refreshments for the Gorosei to get distracted over?
As for Nami, maybe turning out to be Uranus will be a good enough impact because she’s not viewed as much of a significant threat in the verse. Maybe taking Hancock’s title could help as well, but Robin is closer that than Nami ever will be if we are honest with ourselves
here you have it boys and girls. Robin is simply more relevant to the plot than both Nami and Sanji. Honestly you could have these two do the fusion dance and turn into Nanji:
credits to ginyu1992 on deviantart
And they’d still be less important than the character that is known as Nico “The Light of One Piece” Robin aka:
I rest my case