I do not think Churchill was the greatest leader in the 20th century... he was good at a time when there was a war, which needed a strong man, however IMHO his foresight was not that good.
Ex. he made bad judgements when it came to the impact of nuclear weapons in world peace (the balance of power) - the decisions he made in the final year of the 2nd world war was part of the reason we were pushed into decades of nuclear arms race (money wasted, and people scared for their life). Prehaps some of the 50 years of cold war could have been prevented, if he had trusted more on the people arround him, but I guess a world war can make you suspicious of everyone.
Ofcouse he is not to blame for the cold war, but Iīm sure that if he had more foresight, then we could probably have avoided alot of the drama.
Leaders who are good in a time of crises are usual not that brilliant, when we need someone one the bridge to just navigate the ship and not cause problems.
My vote goes to... well funny I canīt really find any great political leader in the 20th century - maybe its because I do not like politicians
