You need an "other" option. anyway, i can't stand the Hittites, but i voted Zulu, cause for me they are 2nd. The Hittites are basically in all my games (all on random civs) and they are always mad and go to war with me.
I voted Zulu (Shaka is a real pain), but only because India wasn't a choice. Ghandi always sneak attacks me, and even when he's too far away to do that, he's always a threat with his uber culture building. I always play with random opponents, but I really hate to see him included.
It's too bad there isn't a way of picking which civs you do NOT want in the game, rather than only the ones you do want.
From that list i went for the Persians. Who as far as im aware are unable to not start with Iron (or at least in my games anyway).
However i actually wanted to vote for Spain my personal Nemesis. Every time i meat them its the same old story. Start of polite sometimes move to gracioues. Then its sneak attack (sometimes even ROP abuse) or an outrageous demand followed by war when i tell them no you cant have Iron and Astronomy.
THE nemesis on the higher levels.
Sumeria, Ottomans, Persia and some more may be stronger - but in that case, they do deserve to defeat you.
Cleo OTOH always ends on another landmass, and threatens to win by sneaky 100k before I can take her out.
I've lost only a couple of Deity games after 0AD (but of course, plenty before...), and most of them were against Cleo.
I voted Mayans/Incans - though it's the Incans I hate not the Mayans. I would have voted India if it were there - I have no probs with the country in real life, but in Civ 3, Ghandi causes all sorts of trouble...