Oh, dear, this thing is getting wildly off-topic. Though I haven't yet played all the civs, and these questions clearly depend on your personal playing style, I think the Zulus (unless, of course, you like the early game rush w/Impis). If you don't dominate early, you're in trouble. Then again, my favorite, the Babylonians, would be pretty bad for those who like to play a militaristic style game.
-Arrian
p.s. WWII: yes, the Nazis slaughtered 6+ million Jews and other "undesirables", not to mention millions of Russian POW's. The USA, along with Britain, the USSR, and numerous other countries (British Commonwealth, etc.) took them down. I find it a tad bit disturbing that a German could so easily brush aside these things because he "can never imagine that stuff." Yikes!
Yes, my country has numerous faults, and has done plenty of things I wish it hadn't (genocide of native americans, gunboat diplomacy, and foreign policy which suffers from the arrogance of wealth and power). Do not, however, take this thread, which is supposedly about CivIII, and turn it into your personal rant about how evil America or its government is - whether it is or isn't, this is NOT the place to discuss it!!!