Lakota, Lakota, Lakota, LAKOTA! Also France, but mostly Lakota. The Power of the Plains is just cheap. No need for farms (Can't even build farms), hidden national borders (so it's harder for your foes to find you), Better Calvary as UUs, And you get food for building Calvary and Tanks! It's indeed paying YOU to kill others! Genius! I also like the French for the Supply Wagon healing, in case I don't get Versailles (Which I always try to build, along with the Terra Cotta Army).