Sorry, but the Gettysburg Address must be listed as his best speech.
This is second. Profound literature and some of the most eloquent words any human has spoken.
Popular opinion agrees with you. But my personal preference agrees with this article. Lincoln was our most eloquent president, and I truly believe his second inaugural address was his best speech. I think his farewell to the people of Springfield is number two and the Gettysburg address a close third.