The captain edges out his first mate — Gear 5's reality-warping gives Luffy the slight advantage.
The two strongest Straw Hats in a clash that One Piece fans have debated for 25 years. Pre-Gear 5, this was extremely close — Zoro's raw offensive power with three-sword style might have matched Luffy's. But Gear 5 changed the equation.
Gear 5's Nika powers let Luffy reshape reality itself with cartoon logic. Zoro's swords — even channeling Conqueror's Haki through King of Hell techniques — struggle against an opponent who can turn the ground to rubber, stretch his body to absurd proportions, and fight with Looney Tunes physics.
Zoro's Conqueror's Haki is devastatingly powerful, and his blade attacks are among the most lethal in One Piece. Against any opponent fighting conventionally, Zoro might win. But Luffy doesn't fight conventionally.
Both have similar Haki levels. Both have extreme durability and willpower. The tiebreaker is Gear 5's reality manipulation.
Gear 5's reality-warping, rubber body absorbing slashes, superior Haki (as captain), and the fact that Oda has consistently portrayed Luffy as slightly above Zoro in the crew hierarchy.
Zoro's cutting power is arguably the highest in the crew. His Conqueror's Haki coating on three blades creates devastating offense. He's tanked damage from Kaido and Big Mom. His raw combat skill is arguably superior to Luffy's.
Luffy wins through Gear 5's reality-warping edge. Zoro is incredibly close — this is the tightest matchup between crewmates — but the Nika fruit's powers provide a slight but consistent advantage.
Monkey D. Luffy also fights
Roronoa Zoro also fights