Stalin's Famine v.s. Mao's Famine

Hitler, Stalin, and Mao are the three biggest monsters in human history.  They killed people in mass via various ways.  Among the three, Stalin and Mao naturally share more than them with Hitlter because they were communists.  Mao effectively followed Stalin's orders on major issues until Stalin's death in 1953.

It is well known that both Stalin and Mao purged their comrades in large numbers through political campaigns. They also killed people with massive famines in similar ways. The Ukraine Famine 1932-1933 caused largely by collectivization forced by Stalin killed about 7 million people, roughly a quarter of Ukraine population.  The Great Leap Forward campaign, a Mao's version of collectivization started in 1957, killed 36 million people, about 7% of Chinese population. 

Ironically Stalin and Mao are still popular in their countries respectively.  This is understandable in China because Mao's party still rules the country with tight control of the press, and continues to treat Mao as a savior of China.  In Russia, Stalin's popularity comes from the fact that he led the Great Patriotic War (WWII).  It seems that many Russians ignore the fact that Stalin executed or expelled 50% of the Red Army officers (including some of the finest - 3 of 5 marshals, 13 of 15 commanders, 154 of 186 division commanders) in 1937, 2 years before WWII, and Stalin aligned with Hitler effectively supporting him starting WWII.  If there had been no purge of the Red Army to consolidate Statlin's authority, the USSR would certainly not have lost so much (including 20 million deaths) during WWII.  In other words, the USSR not only lost over a millions lives to Stalin's Great Purge, but also many millions more as a consequence of the purge.