Ok cool. Now that you mention that realistically which one is more important. Cooking (which apparently nami is the second best chief of the crew and can actually cook well) or navigating the entire sea. Which one is more important to a pirate of the sea?
Nami was cooking from Sanji's cooking book following his cooking methods. Otherwise, the crew is finished in the new world since they can't distinguish between the poisonous fish and the normal ones, it's why it's shown the crew missed him so much enroute to WCI. If Nami was anywhere near to Sanji as a cook then you're making Sanji's entire character redundant, he went through 2 years of training to find a new course too.
Now yes, navigation is more important but cooking is extremely important too and the crew wouldn't survive (especially in the new world) without Sanji's cooking, every crew member has a specialty which the crew can't live without
Also remember Sanji is the far better fighter so he does make up for it
They're both equally important to Luffy's dreams, we've had rescue arcs on
both of them for this very reason. But only thing is, Sanji will take priority when it comes to these parallels because these parallels are more strength based and this isn't Nami's speciality. My bad for the poor wording there. I consider them equally important but the strength based parallels and wings of the PK parallels will go to Sanji