Personally I'm pretty picky when it comes to communist flags. The soviet, Chinese and Vietnamese flags are all classics, but very basic, and all have the same colour pallet. Nothing really differentiates these from any other commie flag. The GDR flag was kinda cool, kinda lame. They just slapped their icon on top of the old national flag. Any flag that just puts a communist icon on an already existing flag isnt that interesting to me, like a lot of american flags just replace the stars with a hammer and gear or something.
Best communist flag? DPRK. Its distinctive and communist. The s tarry plough of the Irish communist movement is very cool, and keeps the same style of the traditional Erin flag. There's a simplified starry plough, but it has a lot less identity
The DPRK has a really good flag but my favourite remains that of the USSR, especially in the 1936-1955 version. It's true to it's revolutionary origins, it's simple, it gets the point across quite unambiguously and it still makes reactionaries seethe.
With that being said I like the Cuban approach of keeping the old flag and associating themselves with past national liberation leaders, thereby robbing gusanos of a rallying point.
The weird thing about the Cuban one though is that it means the gusanos just use the normal Cuban flag even though they’re anti-Cuban and it’s very confusing. If I see a USSR or China flag outside someone’s house or something I’m like “They're probably cool” if I see a Cuban flag I steer clear