The issue I see with this is assuming Churchill doing some good steemed from having some good morals and ethics, same as Stalin, thus being complex human beings. Admitting that between the horrendous acts and ideals they perpetrated and defended they also hold precious and valuable ideas. I don't see that at all. Churchill always looked with good eyes Fascism, saying this of Mussolini: "he thought of nothing but the lasting good... of the Italian people." and "If I had been an Italian, I am sure that I should have been whole-heartedly with you from the start to the finish in your triumphant struggle against the bestial appetites and passions of Leninism."
or: "If I had been an Italian, I am sure that I should have been whole-heartedly with you from the start to the finish in your triumphant struggle against the bestial appetites and passions of Leninism."
In general,
Churchill's opinion of democracy and its values wasn't very ideal
Why Churchill stood against the Nazis when years before he was in favor of appeasing them? Because he saw it as a danger to Britain's hegemony. Why did Stalin stand against Hitler? Because he, Hitler, broke the
non-aggression pact they both had. Maybe Hitler was the worst of all 3, maybe, but all 3 were abhorrent people that just happened to be on different sides of the war.
And their individual value in the war? Well, they surely were leaders and of course their decisions were important. But was Churchill individual input in the war bigger than Alan Turing? The one person who deciphered the German's Enigma machines saving millions of lives? Who was later castrated and condemned for homosexuality by Churchill's government driving him to suicide?
I don't think so.
Did Stalin's individual input really had a big impact on the war or was the 15 million soldiers he sent to the frontlines and overwhelmed the Nazi army?
Those people were horrible human beings that just happened to be on the opposing side of Nazis and don't doubt for a second they wouldn't be on their side if history played differently.