Stalin

Turned his country from a poor serfdom farmland to a superpower.

Mao

Founded the government that turned China into a near superpower for the first time in centuries. There won't be any more British occupations of Hong Kong, or any more opium wars. China is capable of protecting its people from...well, from the West, now. And it all traces back to him.

You are simply letting the propaganda dictate your opinion. As for Hitler, he is a genocidal dictator who killed masses of people. Were it not for the "dictator" part, you could say the same of quite a few current Western leaders.

And there's nothing especially wrong with China's economy, either. It couldn't sustain such an insane rate of economical growth forever. Thinking it will somehow collapse back is just wishful thinking.

As for empirical evidence not being on my side, empirical evidence shows that most notorious dictators and many of the less notorious ones were installed by Western countries because it would benefit them in one way or the other. They didn't arise to lead their countries to success like Mao did, they simply were puppets. Had Mao been also a puppet of the US, I'm sure China would be in the gutter now.