:puts on asbestos undies with chibi fishmen print on them:
I saw the "Who would you get rid of thread" too late to comment. It's an interesting subject, and I think it can be explored in a non-bashing manner if we look a bit deeper at it.
In OP, every major character (and most minor ones) has had a ripple effect in the plot. If there's no Nami, not only is there one less crewman, there's no reason for Luffy to knock Arlong down, his bounty might not have come until later, etc…
If you could change the plot by removing a single character, what plot developments are motivating you to do so? Let's focus on "I want to create YYY, and we can get there by removing XXX", rather than "I want to be rid of XXX"
I can see things like:
Eliminating a flashback character (Zeff, Kuina) to explore where the affected characters go without the tragic flashback ruling their lives and-or how the strawhat crew develops with these people out of play or substantially different.
Pulling minor characters (Cabaji, Ms Valentine) to tighten the pacing of battle scenes
or even removing a Strawhat in hopes to see how they'd do without a major pirate skill set.... how would they get around with no Nami, or fight a Hatchi or Mr. 1 with no Zoro...?
Khaladore/Kuro, because I want to see UsoKa work, and part of me figures that a fully-developed Usopp wouldn't just settle down with Kaya, assuming Kaya still liked him. Ensign "non-axe-hand" Morgan might be a riot, watching him grind his jaw into dust in obedience.
Luffy, because it would result in the comical scene of the (never-attacked) Arlong Pirates trashing the (never-prevented) Krieg-controlled Baratie. See also UsoKa love above and avoiding his interference in it.
Pearl, to drive the Krieg battle to a quicker and more satisfying conclusion. By the time the MH5 settled, I was counting the chapters til the Strawhats sailed.
Again, I'm trying for "what do you think/want to happen by removing someone"... not "who don't you want on board anymore." Kuro's grown on me a bit lately, it's not that I dislike him, it's that he does run interference on UsoKa as Khaladore and as a motivator towards Usopp leaving home.