USSR

A totalitarian regime run on state capitalism, not Marxism.

China (during cultural revolution period)

Now approaching the world's largest economy and has managed to eradicate absolute poverty

Venuzuela

Hamstrung by the USA that stole its oil & sanctioned it to death (literally)

Zimbabwe

Another totalitarian regime & blighted by its colonisation by Britain.

North Korea

Another victim of US emperialism yet has managed to survive because it has nuclear weapons.

Cambodia

Suffered fallout from US war against Vietnam. Again, the Kmer Rouge was totalitarian & committed genocide in a similar way to how Israel is committing genocide in Gaza

The legacy of Marxist Communism isn't nearly as bad as that of capitalism and neoliberalism which could end up destroying the planet.