I like the Democratic Republic of the Congo, if only because I like rooting for underdogs. I love playing as her in Shared Worlds and making her amazing.
I'm curious on how you would make her amazing. With a POD no earlier than 1935, make the D.R.C a regional power in Africa able to defend its borders. Bonus points if she's a strong player in world affairs. Super bonus points if she's on the level of say... Japan by the 80's.