Yes, Maoism was Mao's interpretation of Marx, which was actually quite differnt from Marxism. Hoiwever, Lenin's Russia was pretty darn close to a tru Communist state. It didn't work all that badly in the early years, either. I don't mean to rubbish your answer, Lord, but I have done both courses on Russian 20th century history and 20th century Chinese history. Also, as you pount out, dictators can come from any extremist political belief.
I would pick answer 'Stalin' from your list of choices.