To me Hertzl is the obvious winner. No disrespect to the Chofetz Chaim, a great Jewish leader, and teacher of my great-uncle (see my post "One In Six Million"), but we already had many codes of Jewish law by that time, and there has never been a shortage of people willing to take on that task when needed. As for the whole loshon horo thing, I really could live without all those bumper stickers.
Hertzl on the other hand, created a singularly important event for the Jewish people. If only we had his courage and foresight sooner, great tragedy could have been avoided.
Theodore Hertzl was born Jewish, and raised with little or no Jewish heritage. He was a journalist by trade, and was greatly affected by the Dreyfus affair. He suddenly realized the precarious situation of his people, and dedicated the remainder of his short life to helping his fellow Jew. His actions and opinions were not popular, not within the circle of his professional contemporaries, the "intelligensia", and not even among his fellow Jews. This did not deter him at all - he had tremendous vision, knew what was right, and acted on it. Hertzl sacrificed his career, family life and friends for his people. His ahavas yisroel (love for his fellow Jew) was unrivaled.
The Agudas yisroel version of history demonizes Hertzl, calling him anti-religious, mocking the Uganda idea, and trivializing his accomplishments . Perhaps they are jealous that a "Hertzl" did not emerge from their ranks. Perhaps they can not admit to any greatness outside of the" daled amos" of halachah. But we must remember the words of Chazal about Charvonah in Megilas Esther. They call him "Charvonah of blessed memory" because he simply told the king about Haman's gallows. If we can venerate a gentile for a simple action can't we recognize a Jew for a lifetime of sacrifice for his people? The Agudas yisroel and the charedi world should not be so haughty as to think they understand all of G-d's plans. After all, didn't Mordechai ask: "Who knows? Perhaps this is precisely why G-d placed us in this very situation?"
Who knows? Maybe G-d is thinking "You were in exile, oppressed by cruel people in strange lands. You prayed for help, and I sent it to you, and you don't even recognize it or thank me for it."