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
Angola's flag is pretty cool, I like gears on flags