It's hard to say for sure. Ultra Instinct Goku is incredibly powerful, but Merged Zamasu has some unique abilities too. It could go either way depending on the circumstances and how the artist portrays their battle.
In most fan manga, it seems Ultra Instinct Goku has the upper hand. His new form gives him enhanced speed, strength, and reflexes. But Merged Zamasu's immortality and fusion powers can pose a significant challenge.
Well, it really depends on the creative direction of the fan manga. Sometimes Ultra Instinct Goku might be depicted as dominant due to his raw power, while in other versions, Merged Zamasu's strategic skills and durability could give him the edge.
The best chapter pointer here is Chapter 242, "Jiang Yan's Dazzling Transformation Journey". It opens with Just when Jiang Yan called to heaven and earth in vain, he looked up and... and closes on Just as he pushed open the creaky wooden door, a huge dead spider fell....
Chapter 222 is the strongest chapter-level answer because it starts from How come they're even live streaming in a reality show?! and follows through on She was certain and sure that she saw scheming in them..
Look to Chapter 277 for the clearest answer. It begins with After reviewing that document, Zhao Lang's brows knitted together slightly., keeps building through Huh, the last call was actually related to Shang Shaojing..." Zhou Xu..., and lands on He really has been too nice to him..
The best chapter pointer here is Chapter 235, "Bungee Jumping in Ethiopia???". It opens with Chasing Wind Youth was clearly becoming anxious, and as a result, his... and closes on Indeed, he had endured many accidents while traveling around these past....
The best chapter pointer here is Chapter 242, "Jiang Yan's Dazzling Transformation Journey". It opens with Just when Jiang Yan called to heaven and earth in vain, he looked up and... and closes on Just as he pushed open the creaky wooden door, a huge dead spider fell....
Chapter 259 is the strongest chapter-level answer because it starts from While the villagers of Chixia Village were all immersed in the revelry of... and follows through on It wasn't that he was scared..
The best chapter pointer here is Chapter 274, "Post-Traumatic Stress Syndrome". It opens with Upon hearing this, Officer Xu became even more excited, but catching a... and closes on I believe with some rest, he will recover." Relieved at last, Hu Zi's....
A practical answer is Chapter 214, because it turns the idea into a concrete scene. The chapter opens with Director Sun fell silent for a second., adds pressure through She says what's on her mind, which sometimes makes being friends with her..., and ends on Even when Wen Jiaojiao fanned Richards'.
The best chapter pointer here is Chapter 235, "Bungee Jumping in Ethiopia???". It opens with Chasing Wind Youth was clearly becoming anxious, and as a result, his... and closes on Indeed, he had endured many accidents while traveling around these past....
If you want the clearest chapter reference, go to Chapter 254. Early on, Just when everyone thought that Jiang Yan wouldn't last long and would...; later, the chapter leans on The first day, he was bitten by mosquitoes until he could bear the pain no....