My favorite Bleach character is of course the most easy to hate.
It's his attitude. His attention to detail, single mindedness, his sense of honor, duty, and family. He seems cold and aloof, but you can see he protects those who he loves, and he may never say it, but actions speak louder than words. I think that he's just cut himself off to devote himself to his family as he believes that his love arrived once in life, and he's never destined to to experience it again, or has no desire to. That's just me though. To me he is, in some ways, the true samurai of the series. His life is Bushido, just replace the lord with the SS.
The beauty of his heart can be seen through his Bankai. His sword turns into cherry blossoms.