Yes, gentleness and kindness is perhaps the most emphasized quality of Sanji throughout history and that made several enemies stand by him, and this was due to his interaction / creation by his mother Sora and Reiju, while Zeff was the one who taught Sanji his moral principles.
In the end, everyone knows that Sanji has all the qualities of a conqueror, and that is leadership, willpower, determination and the ease of recruiting allies, but I'm not sure if Oda will give this to Sanji.