The heavy facial scarring makes things tough... He might have to grow an Ozai just because it's the only thing that will not highlight his inability to have sideburns. Though I like the Sozin, it probably has too much stigma behind it.
Wait, where's the Azulon? Or is that just a grayer Sozin?
I'm voting baby face or Ozai. I know Ozai was THE WORST dad ever! But I feel because of his burn, any of the sideburn inclusive looks would look lopsided and asymetrical to the point of being funny. Since he can't really grow a sideburn on his left side. You know what I mean? And the Ozai look with say a moustache would make him look like a porn star. Which Zuko kinda is. Also: Nice drawings.
Love the Iroh look on him! I agree with the Ozai thing -- I know if my father abused me, I wouldn't want to look like him everyday in the mirror. The Iroh look just rocks though. I've always pictured an older Zuko with that kind of beard.