Well, seems very unanimous for Japan, but I have another, third option: An MDS 1.6 AAR as the United Kingdom. I forgot to mention this idea in my original post, but I think it could be fun as well. The main goal of a British AAR would basically be to rebuild the British Empire, and would involve probably having to invade and puppet countries like Canada, Australia, New Zealand, South Africa, as well as total annexation of lots of countries, including the powerful nuclear armed rival states of India and Pakistan. However, Britain is much weaker than Japan, and politically would be hard to justify going on a crusade to rebuild the empire.
I guess I will go with Japan, but I would also love to hear some other suggestions that people have. Are there any other ideas for an MDS AAR?