My preferred ruleset for this period is Chain of Command using 28mm figures although it may not be suitable for larger games. In 28mm there are a wide variety of ww2 figures to choose from: Americans can be Artizan Design, Crusader Miniatures, Assault Group and others. British can be had from the same manufacturers and some of the smaller nations can be adapted from other ranges.
The Chinese and North Koreans are harder to find. Only 1st Corps makes Chinese figures and these are one small range of eight. They are very nice with varied poses and fur hats. Copplestone’s back of beyond range provides a good source of Chinese in fur hats with rifles and type 24 machine guns along with a nice heavy mortar set. The hats need to be filed a bit where they have a peaked cap. This gives that shapeless look so beloved of the Chinese.
Then we come to the North Koreans- basically there aren’t any. I looked everywhere for communist figures and the only 28mm figures remotely similar are Mongrel Miniatures Afghan army types. So, I took the plunge and decided to get my own range started.