I have a lot of favourite characters when it comes to Bleach, so you'll have to settle with my top three favourite characters lol.
(In no specific order whatsoever!)
Kurosaki Ichigo - Being the main character of Bleach, you learn the most about him, and therefore, get to know him the most. He's adorable in that he has a rowdy personality, yet he cares so deeply about those around him. I think it's really cute when he's embarrassed about something, and not to mention - that's a hell of a body he has!
Kuchiki Byakuya - Who wouldn't fall for the mysterious, powerful and good-looking authority-man? Kubo did a great job in drawing me towards Byakuya's character, and again, talk about those muscles..!
Shihouin Yoruichi - In my opinon, Yoruichi is, by far, the most notable female character in the Bleach series in terms of skills. I'm glad Kubo included Yoruichi's character, as this shows that he doesn't believe in sexism as other mangaka, and the fact that he didn't make out Yoruichi, nor other female characters, to be weak and useless, is also another added bonus.