Babylon I think. Their bonus comes into play earlier with the fast academy. You can tech philosophy really fast and get NC building before needing to tech composite bows. You can rely on bowmen for early defence as well, and you can always build the walls if you get attacked, which pretty much make cities invincible early. Furthermore you get the most out of their bonus even if you just run great scientists, whereas with Korea you need to run more specialists to get the most out of it, which means you're not growing as fast and risk generating non-scientist great people which will slow your tech down.
In the end you're getting about 1.5x as many acadamies, plus an early bonus academy, plus an early defence bonus, and the guarantee of generating pretty much just great scientists even if you want to run other specialists.
Ironically I think Korea is one of the best civs for cultural victory because you can run a bunch of great artists and engineers and still not fall behind on science.
Just looking at the pure math of it.. The early academy gives you +6 science, so until you're running 3 specialists you're not even breaking even as Korea, then Babylon gets their second academy out quicker too.. for one city games it doesn't even seem close.