Sorry for the rant but:
If he wasn't white or west of the Iron Curtain, he would have gone down in history as a war criminal. Had a Nazi succeeded in committing the same actions Churchill had, they'd have appeared at the Nuremberg trials.
Funny how in modern times, we get uppity about drone strikes, which may or may not kill civilians on a case-by-case basis. A small offence compared to the fire bombing of cities in which hundreds of thousands live, specifically targeting civilians. Yet we revere the leader behind the latter.
Winners write history, I suppose, and propaganda cements them as the good guys. Needless to say, I am not a fan of his.
In my interview for a place at Oxford, I expressed a lack of admiration for Winnie, and floundered when asked why. Needless to say I went to a lesser hall of learning.
With the advantage of hindsight and learning, I was both wrong and right, just as you are wrong and right.
War is acts of barbarity. All of it. Virtually all of them have been persecuted using methods distasteful to any civilised man. Is firebombing civilians justified? The answer must surely be no - but equally, if you are convinced that the action is required to save your nation and the lives of its people, the answer must surely be yes.
Churchill ordered atrocities. He blundered. He as monstrously unfair and unkind to no small amount of people. Creating a list of his flaws is not difficult unless you want to be thorough.
However... I believe that, objectively, fighting Nazi Germany was a noble and fine thing. I cannot agree with a statement that says only propaganda made the people fighting them the good guys. Churchill's reputation is not simply a matter of west-o-centric history. It is a matter of being (un)fortunate enough to be the right man in the right place and to shoulder the burden of resisting and defeating one of the most abhorrent regimes in recent history. If Churchill had ordered firebombings in order to secure Gelsenkirchen for Britain, or to keep back forces attempting to stop ethnic cleansing, or to remove overseas irritants to strategic interests, then he would have probably gone down as a war criminal. But he didn't. He did it in an attempt to remove a meglomaniac racist intent on military subjugation of everyone nearby. It is understandable that people are prepared to overlook/forgive/excuse bad things done in pursuit of a good aim.
Moreover, Churchill might not have had great morality, but he was a great man. He was a hero in the sense of the ancient Greek sense of the word, an exceptionally talented individual. It is difficult to imagine any other politician of the time who have had the ability and traits to commit Britain to such a fight and then see it triumph. His non-existence or failure creates a genuinely plausible scenario in which modern day Europe doesn't challenge racism but rather encourages it. He is revered both for his ability and for the cause he used it. Like him or not, he was by at least two measures of the word, a great man (the fat git).
So... yeah. No one deserves a totally free pass for deliberate strategic bombing of civilians. And there were many other things to judge him on. I was lucky enough to inherit a number of histories on the Second World War annotated by my Great-Grandfather, a man who knew Attlee very well (he also turned his back and walked out when introduced to Bomber Harris). The annotations are very acid when it comes to Churchill. But on his total balance sheet, I would suggest that the positives of his life greatly outweigh the negatives. I think you do him a grave disservice to place his crimes as the first measure of the man.
I'm going to second smartcooky. For breadth and importance of achievement, Sir Winston Churchill.
Martin Luther King would probably be my first choice though.
For a left field choice, Robert Heinlein. An incredibly persuasive and inspirational writer.