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 Spanish third Republic's (and more radical variants of it ) is really cool because they took the old one & changed a color into an even more pleasing pairing. Purple is really rare on flags because of imperial/expensive connotation but its the goddamn 20th century purple aint been prestigious for 500 years
a good flag for this site is the mexican liberal party's and speaking of the mexican revolution, modern Zapatistas' flag fucking rocks. a consideration for non sectarian org would be to have a design that could accommodate the main color being either red or black
Soviet Union Zero flag
"all the soviet, none of the hierarchy"