I say try playing Korea. They are stuck between Ming and Japan, the two larger powers, separated from Japan by sea and Ming by means of Manchu as well as the sea. Their provinces is decent and manpower is decent, and can play similarly to Japan using Manchu as a buffer (As long as Ming doesn't eat it up of course), but starts with a harder starting position and Japan itself to deal with. From my games, it also seems that Japan tends to have good relations with Ming, and it also tends to be a naval power, making some pretty hard juggling to do.
I mean, hard, because seriously, it's rather pretty difficult to get a foothold on the Indochinese subcontinent for one thing- especially since it's hard to keep a positive income and tending to get bankrupt when engaged in a major war for the first few years, and Korea doesn't have Japan's manpower either. Not only that, Manchu tends to like to go southwards which can be annoying or even threatening at times and Korea doesn't even have a CoT.
And oh lord, Confucianism ahoy, meaning a 50% tax penalty unless you switch to hindu or something fast.