This is very similar to what I did on the thriller back forum ... But I don't know if '' quartermaster '' would fit exactly in the definition of the role that Sanji has been playing in the story.
I mean, Sanji is definitely the heart of the team (
@Soleus said something like this). It is he who protects the weakest strawhatz most of the time, it is he who saves them dozens of times and Sanji is the one who leads and advises them many times throughout history. He has an incredible role on the team, he also has a very deep relationship with Luffy, often looking like he is the immediate one.
There are idiots who do not know the character Sanji, and do not know the true mindset of his personality and willpower.
The term ''Sanji has no willpower like Luffy and Zoro, so he won't be top tier'' is dumb and problematic on so many levels ...
Sanji's willpower is not directly driven by the dream of finding all blue. His willpower is completely linked to his proactive role within the crew to save and protect the weakest, per statement:
I agree that, Sanji's willpower in getting stronger, obviously is not linked to his dream of finding all blue, he doesn't need to be strong to achieve his dream. Sanji's entire evolution of strength, development in willpower is driven to protect people and have the prominent role on the team, even being the wing that makes Luffy fly.
Sanji is like Whitebeard and Sabo. All their willpower to get stronger is to protect who they like: