Ever since Toph invented metalbending in Avatar: The Last Airbender, this sub-skill of earthbending became one of the most unique martial arts styles in the Avatar world. Toph went on to be the patron saint of the talent, establishing her Metalbending Academy to spread knowledge about the art form as well as building the Metalbending Police Force of Republic City to protect the fledgling United Republic. By the time of The Legend of Korra, there were plenty more masterful metalbenders, and two of the best were Toph's daughters.
While Lin Beifong followed in her mother's footsteps as the Chief of Police, Suyin forged her own path in founding the city of Zaofu. Both became metalbending masters in their own right, but even by the end of the series, the question remains: who is better?
Lin Beifong appeared early in The Legend of Korra, where her domineering presence proved all the more fearsome in battle. Whereas most earthbending styles revolved around grounded stances and connection to the space around a fighter, Lin and her Metalbending Police proved incredibly acrobatic in combat, wielding spools of metal cables like Spider-Man's webbing to navigate their terrain. At the same time, her raw power was frequently demonstrated as she hurled massive boulders, created stone barriers and even ripped a metallic airship asunder.
Suyin's talents diverged by emphasizing the acrobatic style that reflected her background as a dancer and a free spirit. Suyin frequently used jumps and leaps she integrated into her combat style, which was similarly assisted by her use of metallic cables, but she also displayed some of the most versatility of any metalbender in the series. She could create weapons and armor on the spot, strike quickly with a variety of different attacks and most memorably, combined those talents to encase the Combustionbender P'Li's head in a metallic shell at just the right time so her opponent's own attack backfired.
In terms of comparing the sisters, perhaps the best evidence is their showings against one another. One of the earliest showdowns the sisters shared left Lin scared from the confrontation, where her attempt to bind Suyin with a metallic cable caused Suyin to lash out, slice through the cable with a quickly-produced blade and then rebound the wire into Lin's face. The instance scarred their relationship from that time on, but the emotional wound would only really heal in the aftermath of their final duel against each other in the episode appropriately titled "Old Wounds."
The two have it out in the middle of Zaofu, and the fight proves both remarkably even and an excellent display of their different talents. As Lin launches repeated assaults of devastating force, Suyin ably navigates her way through the projectiles before delivering attacks of her own. The duel finally ends when each charges down the other with their mass of material weapon-ready, but the fledgling Opal interrupts them. The fight ultimately seems inconclusive, but there is one detail that sticks out to any Avatar fan wondering which sister was truly the better: Lin was sick.
The episode revolved around Lin's acupuncture sessions that allowed her to reevaluate her past experiences with Suyin, and it was the interruption of one of those sessions that caused Lin to confront Suyin with the duel in the first place. However, just before Lin leaves, the acupuncturist warns her of the damage to her health that interrupting the session could cause, and indeed, throughout the fight, Lin was haggard and sweating as she barely hung on. And yet she still fought evenly with Suyin, whose physical condition was pristine.
The clear implication is that in a fair fight, Lin would clearly have the upper hand. Her years policing and participating firsthand in the fight for justice likely kept the elder sister's skills well-honed over the years even as Suyin's once adventurous life retired into more domestic and political duties. They may have seemed even, but to anyone paying attention, it seems that Lin was just flat out the better metalbender.
