I dont know. On one hand I have to imagine Goku is mentally retarded since he just jets off on a whim. besides, maybe this is normal parenting in the Saiyan world. I mean, just looking at the way vegata grew up, maybe Goku's the easy going dad, and other saiyan dads just go off and spartan that stuff by leaving their kids on some alien planet and expecting them to come back home on their own.
On the other end, Ozai physically scarred his son. I get the honour thing, and how this is a different culture, but he physically scarred his soon with fire, which could have easily just burned him alive and killed him. At least Goku never actually attempted to kill his son.
I dont know. I guess i'd have to say Ozai, because no matter what Goku does, he can just dragon ball wish this stuff, and even while he was gone, his kids had a group of people. Zuko only had Iroh, and his mother for the early part of his life. And really, how bad of a father are you when your son actually comes back to you, realizes that you're a dick (again) and leaves you (again) and this time helps bring you down. At least Gohan (at first) didnt want to go with Piccolo on his own. Piccolo just stole him.
Plus Goku always had a good reason to not be there, as he was saving the world. So in a way, he's actually doing the greatest thing he can for his son, by saving him. And Goku spent enough time with his sons while he was alive, and even left the planet and searched the galaxy with Pam.
Decision: Ozai
EDIT:
Yosato said:
Goku knew he wasnt strong enough to beat Cell, but Gohan was. However Gohan is a pacifist (something Goku accepts and tells him its oka, and he only has to fight when his friends are in a very real threat of danger), so he needed to have him pushed. Lets not forget that Gohan does manage to summon the power taught to him by his father to beat cell then spares him (a lesson he learned from hsi father). THen cell is his dick self and threatens to blwo up the world and look who sacrifices himself so that hsi sons and friends can live (hint: its Goku). Then when Cell comes BACK fromt he dead, Goku reaches from the dead to help his son summon the confidence and power to beat cell (again), before congratulating his son and telling him what a great job he did and how proud of him he is.
Also, Gohan didnt RUN to piccolo, he was KIDNAPPED by piccolo initially, and developed a stockholm syndrome to him. Goku was kinda dead (what with sacrificing his body to save the world and his son [who he specifically mentions as doing this for]) so he couldnt really do anything about that. then afterworld, Piccolo became an uncle figure to Gohan, and arguably the only reason Piccolo didnt just destroy the shit out of the planet (besides kami). So even then, Goku oncce again saved the world, turned the heart of an evil to good, and gave his son soeone who could watch over him and protect him while Goku was gone. Goku set it up for Gohan to have a father figure, and even then Gohan still thought that Goku as his father, and the big parental father figure in his life.
Ozai just said get the fuck out, not even caring enough to give Zuko someone to travel with, and Iroh left with Zuko out of the good of Iroh's heart and love for his nephew in place of his lost son.
Gohan learned all the greatest lessons in life from his father, or his friends (who had been influenced or taught by Goku). Zuko pretty mch had to reject everything his father taught him to even have a chance in society. At least Gohan had a place among friends, and could get by. Goku never said dont study, he just said lets have fun. If anything, Goku saved his son from being so socially inept after all that book learning.
