Difficult question. I’ll try my best at making my thoughts somewhat legible.
If you ask 10 different people what communism is, you’ll get 10 different definitions, so just to be absolutely clear, when I think “communism”, I think of authoritarian, centralized socialism where the state is the ultimate arbiter of all things. Communism has proven to work extremely well and be pretty nice at the level of a town or village as long as everyone has the option to stay or leave (for example, kibbutzes). The important part here is the voluntary nature and human scale. This amount of centralization and power is insane at the level of a state.
I think any authoritarian government has certain inherent problems, and leads naturally and inevitably to institutional paranoia. This is extremely bad for citizens. Not all authoritarian systems are equally bad, but this part I feel is unavoidable in any authoritarian government.
I am a big proponent of socialism, especially syndicalism (although recently, the more I read about anarchism the more it makes sense), but it has to be in a system where people have control over their own lives.