As long as I'm watching, I might as well finish up this round...
Alexios I Komnenos (Byzantium) 33
Hezekiah (Judah) 18 (21 - 3) -- I've been more or less neutral on Judah/Israel because, even though I'd like to see them included, I can also the arguments against them. I think third place is adequate for Hezekiah, who would be my choice should Judah/Israel be included: he's less significant than Alexios Komnenos and less needed than Powhatan.
Powhatan (Powhatan Confederacy) 27 (26 + 1) -- Let me explain why the Iroquois should not appear again despite being beyond question the most significant civilization in post-Columbian North America: in Civ1 there were no Native American civs, in Civ2-4 there was one Native American civ (quite literally in Civ4), and in Civ5 there were two. That suggests the very most we can hope for is three, and I wouldn't hold my breath on that given that there wasn't even one in the base game--discounting the Aztecs, there wasn't even a single civ indigenous to the entire New World in the base game. So I'd be astonished if we even got two again. Given that, there is absolutely no sense in repeating the same civilization over and over again, no matter how significant. The Powhatan Confederacy would fill the same gameplay niche as the Iroquois, represent a linguistic clade and group of cultures that have never had representation in civ before, offer a far better leader choice than any the Iroquois could offer, and be a choice whose significance would not be questionable (like, say, the Shoshone): Powhatan ruled over a rather large stretch of land with over forty tribes under his command.