Babylon: Ingenuity - 34
Korea: Scholars of the Jade Hall - 37
Poland: Solidarity - 32
+2 to Poland. Seriously, it's the best one in the game. And I vote it especially because the reasoning of other people is severely flawed. -2 because it's boring and just gives Social Policies? Yeah, Neby's free Great Scientist and more GS generation is so much more fun, not to mention Korea's fascinating +2 science per GP improvement/specialist combined with the oh-so captivating research agreements with yourself.
Not to mention free Social Policies give you more options and choice. Even suboptimal policy trees are a good choice with Poland, because you can just afford it.
Underwhelming? How is an entire policy tree for free underwhelming? Even if you only took inferior ones like Honor or Piety, that's still +15% combat strength, 50% more GG generation, faster melee unit creation, free GG, +1 happy/2 culture per garrison, 50% faster raising of useless XP buildings and gold per kill all in one ua. Obviously you won't pick Honour (at least not only that), so you can just get a Tenet or two, and I don't know, Patronage/Commerce/Liberty/Naval/Aesthetic policies.
-4 to Korea. It's superior to Babylon's, but simply doesn't deserve to be this much ahead, as they're - more or less - equal, with Sejkong having at best a slight edge.