Artificial Intelligence
I believe that the most beneficial intelligence to replicate would be the ability to perform complex manual tasks. This would be very helpful for creating all kinds of rescue robots or robots that can operate heavy machinery and accomplish tasks that humans cannot. Another Very beneficial artificial intelligence to replicate would be the ability to solve mathematical problems. This would could help us advance in mathematics and unlock newer technologies.
I feel as if the hardest artificial intelligence to replicate would be the ability to solve mathematical problems. This would be very hard because it took us so long to create functioning calculators and to implement this into an artificial intelligence would take a very long time and prove to be very difficult.