Marx is the most important critic of capitalism and dismissing his critique with “Stalin though” does not really address the point. Even if you think Marxism is totally bad in all it’s forms that does not mean that Marx’ critique of capitalism is invalid. You don’t have to be a cook to know if a soup is over-salted.

There are better critics of capitalism, social democracy has long tradition. Marx never visited factory and hated dirty workers. He was an "intellectual". Actually go and read his books, not just quotes.