Philosophical and Creative are great boosters for science, because of the double speed on both Libraries and Universities. With that in mind, the Koreans give the Saewoon (University) which boasts a 35% bonus to science instead. Strong(er) but not great by any means. And the unique unit is of dubious strength. Bronze Working is available at 4000 BC, though. Arabia makes for a good snowball, double speed on Madrassa and easy Great Person generation, as the Madrassa has a whopping 4 specialist slots. Egypt for a similar reason, and both allow for maybe founding a religion early, allowing for good use of the possible Great Prophet. Weaker on higher difficulties? Romans would be great, but that's 90% because of Praetorians, not the Forum. Forum is actually stronger on non-Philosophical leaders because the returns are diminishing, unless you're going for a gimmick strategy. A 25% boost is about 15% more Great People over the course of the game. This drops to 13% with Parthenon, 10% with Pacifism/Philosophical, and 7% with both. Oh, and there's National Epic, too.