Turkey
If you could go back in time and change one event in the earths history where would you go and change?
I'd pose as a senior German official and kill Archduke Franz Ferdinand.
Given the time spent thinking about this excellent question, I feel obligated to give an explanation. A senior German official killing Franz Ferdinand would start a war between Germany & Austria. With two close allies divided, WWI is averted. With WWI averted, the Russian monarchy is retained and Russia never lurches as far as communism. With Russia not at polar opposites against the capitalist West, the cold war is averted.
As Germany and Austria are traditionally friendly, the peace negotiations are not as debilitating towards Germany. As Germany is in a better position, Hitler doesn't come to power; WWII is averted and the Holocaust never happens.
The lack of major international conflict delays the US development of nuclear weapons, ensuring they are not used should Japan still attack the US.
Eat Christmas pudding plain, with cream, custard, or ice-cream?