Ok, for all of you that are comparing Kaname and Zero. Kaname is hundreds to thousands of years old. He is a Kuran ancestor, who was resurrected. This makes him much more older, and wiser than Zero. Comparing Kaname and Zero, is like comparing an ninth grader with a university student.
Both Kaname and Zero are selfish in their own rights.
Kaname treats Yuki better, only because she is his supposed sister. He takes care of her, only because she is his family. He does not share the same feelings with Ruka, who is there for him all the time. Ruka has done, and stayed by Kaname more than Yuki. It's true that Yuki did not have her memory for the most part, but Ruka did more than just stand there. She defended Kaname, and fought to protect him. So, why did Kaname choose Yuki and took care of her? Because, she is family.
Zero is obvious. He was young when he lost his parent's to a pureblood vampire. His brother left him, and went against him because of a pureblood. He was trained from a young age, by the world's best Vampire Hunter to kill the like's of purebloods. So, why is he so arrogant towards Yuki, when she turned out to be a vampire? Because, it run's in his family to be vampire hunter's. He hate's pureblood's, because he hates what happened to his family. Zero may have issues, but he still remembered Yuki during the end of season 2 in a flashback. He will miss out on her, even though it might not look like it.
Since this is a forum about Kaname, let's go back to him. Who wouldn't want to be like him, or with him. He is old, and wise, but in a much younger body. He is a greatly respected figure, who is also much smarter than most of the character's in Vampire Knight. He barely shows any emotions, of the loss of his parent's. He is clearly one of Vampire Knight's most valuable, and strong characters, who shaped the Vampire Knight (Zero) to attack Rido. He is someone, that Zero will never be. The sad part is that he has a sinister future. The main reason why Kaname is so great is because, he was willing to let Yuki go at the end of season 2, even though he waited ten years without her.
Kaname may be a great character, but he is also selfish during times. He let Zero live, only because Zero protected Yuki. He could have saved a lot of level E vampires, before turning, but he did not care for them. His commitment is mostly to Yuki, and that's it.
Hope this explains a lot. Thank you.
I did not use spoiler's, as I summed this all up from anime.