To quote
@Den_Den_Mushi
"
Sanji is actually quite a poor leader. I would not describe him as level-headed; in fact, when things reach crisis point, he offers few workable solutions and often loses control of his emotions.
When Luffy challenged Aokiji to a duel, Sanji slammed Usopp into a wall and blamed him for not stopping Luffy, which was both unproductive and illogical. What could Usopp possibly have done? Zoro, on the other hand, acknowledged that while he personally felt frustrated, Luffy’s wishes should be upheld first and foremost.
During WCI, instead of believing in Luffy or at least trying to explain the situation that Zeff was in, Sanji kicked him in the face, insulted him and showed zero understanding of his own captain’s personality. There was no need to be violent towards Luffy, he was not leaving regardless. Having been through 3D2Y, having read about Luffy’s attempt to save Ace and having been present at Enies Lobby and Arlong Park, there was no excuse for this behaviour. Sanji let his emotions get the better of him, and took his frustrations out on his Captain.
Now, if you had to choose a leader, who would you choose? The tough but fair leader who remains logical and tells you what you need to hear rather than what you want to hear, or the hot headed, emotional leader that violently attacks his own crewmates to alleviate his frustrations?
I believe I’ve made my point clear.”