I can't think of any successful communist countries. They've all quickly devolved into totalitarian regimes, or else they've had to adopt a capitalist economy because a communist economy just didn't work.
This why the right conflates socialism with communism, because they don't want to acknowledge that northern Europe is absolutely crushing it in both wealth and services.
These countries are obviously doing something right and the rest of the world should take notes from them
What they're doing right is a mixture of rather progressive social policy (in the process of being abandoned in favour of the extreme right), and exploitation of poorer countries through unequal exchange. It's high-school level knowledge of colonialism: import raw materials and agricultural produce from poor countries at low prices, export high-added-value goods and services at a high cost. If every country were to adopt that model, it wouldn't work because there'd be nobody to exploit. I suggest you read into the concept of unequal exchange
Northern Europe also depends heavily on Unequal Exchange, and has seen sliding safety nets. They are happiest because they are generally the wealthiest, and that wealth must be seen in the international context, as they do not practice Autarky.
They've all quickly devolved into totalitarian regimes
Tell me you haven't studied the political structures of Cuba and the USSR since the 60s without telling me you haven't.
While both countries have a high level of concentration of power on bureaucratic elites when it comes to big policy, there were/are a ton of democratic mechanisms that simply don't exist in the west. Extremely high rates of unionization with unions having big decision-making power in the workplaces and outside them, party-membership being encouraged with extremely high rates of it compared to western democracies, neighborhood councils having actual decision-making power both through legal mechanisms and through funding to enact desired local policy... If you want to learn of a particularly interesting instance, you can read the book "how the worker's parliaments saved the Cuban revolution" by Pedro Ross, in which it's detailed how massive democratic participation in the early 90s after the dismantling of the USSR ensured the survival of the country in an astronomical economic crisis.
You also say this as if western countries were democratic at all, as if putting a ballot once every 4-5 years ensured popular decision-making. Study after study show that public support for policy in the west is a terrible predictor of whether that policy is adopted or not, and vice-versa, i.e., public opinion and policy are uncorrelated. The fact that you can't easily point to a particular authority responsible for this, doesn't make the system any more democratic, it just makes it look less authoritarian. Who in France supported the rise of the retirement age? Who in Europe supported austerity policy after the 2008 crisis? What percentage of US citizens don't support socialized healthcare?
Orrr the US overthrows their government and replaces them with a fascist regime or monarchy whenever there's even a hint of socialism. Latin America, Asia, post-ww2 Europe... they have a tendency to do that a lot.
The only ones we know of are all authoritarian regimes because they're the only ones which actually have enough resistanace from outside interference to not fall victim to the USA's shenanigans. Democracies are extremely vulnerable to outside influence / bad actors, and when you have the most powerful country in the world working to destroy your democratic government, without the centralization to resist that it's no use fighting back. We created this problem.