Wings Statement is neither about Power Levels nor the relationship between Zoro & Sanji
You people only focus on comparing them Two but never focus on the whole reason "Wings" Word was used
Wings of who? It's Luffy ofc
An Unbiased Analysis should focus on Luffy to understand what Wings mean, not Zoro & Sanji
Oda is telling you that Luffy needs both Zoro & Sanji to fulfill something
And it's not to become Pirate King, cuz the Entire Crew will be responsible for helping Luffy reach such Title
It's for his Second Dream! In other words, it's a Foreshadowing, that "After" Luffy reaches Laugh Tale, his Secret Dream will be fulfilled thanks to Zoro & Sanji
Now let me ask you, what's the Moment in entire Manga that is only Exclusive to Zoro & Sanji where rest of Crew were Absent?!
It's obviously "Nothing Happened" Moment
That Moment happened "After" Luffy brought back The Dawn (People can survive the Sun) & defeated Moria
(Who was literally the Crew's Final Villain from Pre-TS)
So there is a Foreshadowing that "After" Luffy becomes Pirate King & defeats Final Villain
Something will prevent Luffy from fulfilling his Secret Dream (Which Luffy admitted must happen after he becomes Pirate King & he ain't sure if it's even possible, hinting that Luffy will still need some Help then)
That's where the Wings Statement becomes more clear, as Zoro & Sanji are the ones who will fulfill Luffy's Secret Dream
Now if you go check their Fights against King & Queen, how did they End?
Sanji Unlocked Stronger Flames while Zoro declared himself King of Hell & then encountered a Shinigami
The idea is very simple, throughout the entire Story, Sanji is being built to handle as Much Heat as possible, while Zoro is being built to handle Death itself, in other words, what stands in the way of Luffy fulfilling his End Dream are Extreme Deadly Heat & Death itself
Since Luffy will be Powerless at that moment (After defeating Final Villain), someone must take him to where he needs to go & another person must protect him from Death, this is why both Zoro & Sanji are portrayed as Luffy's Right Hand Men & Wings
Cuz at the end, Sanji is the Man who can carry Luffy & Fly as if he is his Wings, while Zoro is the Man who can even defend against Death!
Why? Because Sanji is on the Path of reaching Biggest Heat Resistance, while Zoro will Unlock a Black Blade
Black Blades are Special cuz they are the only ones that can "Hurt or Touch" Death itself (Oda even spoiled us who this Character is when he said that a Man with Eye-Patch will appear at the very end of One Piece). While Sanji is the only one who can resist coming close to the Sun's Surface
In other words, the method to save the World which happens to be also Luffy's Dream & what the Straw Hat symbolizes & it represents the Ultimate Form of Freedom as it means going to a place that "No One" ever reached, is none other than Luffy being taken to the Sun!
Sanji will carry Luffy & take him to the Sun, while Zoro prevents "Final Mysterious Figure" from stopping them
And during this moment, Zoro will finally call Sanji by his Name as they say Goodbye, and it will be Final Death in One Piece & it's Biggest
(Sanji's Kindness will indeed be his End & he will be remembered as a Legendary Hero & The boy who flew too close to the Sun)
While Zoro will be seen as Strongest Warrior who was able to fend off Death itself
If someone asks, tell them "Nothing Happened"