my unpopular opinions chained with each other:
- Haki man is a real, independent category/type of fighter. The correct term is haki user, just like Vergo's statement when fighting against Smoker in SAD factory. Vergo said "If you face a better haki user like me.." indicating that haki can be used as a primary skill / weapon instead of bamboo. Indicating further that there is, out there, the strongest haki user.
- WSS is the most narrow of currently revealed strongest title. If there is a strongest martial artist, strongest spearman, strongest gunman, strongest Devil Fruit User, Strongest Haki User, WSM is by portrayal the same tier to these guys. Hachi and Hyouzou are fishmen but they're swordsmen too, so it broaden the title regarding species/race.
- WSM is wider than WSS, but only consisted of male, since the raw term involved the term "Otoko" (male) instead of japanese word for human.
- WSC encompasses all living thing. The raw term is "Seibutsu" (living biological thing). In-manga reaction of the SHP to the epithet of WSC is "so he isn't even human?", even though can imply that the title doesn't include human, but it doesn't directly oppose that human is among creature.