I think Orihime may be my favorite. She changes a lot through the story, and just when she hits the peak of becoming so much more to the group, she gets kidnapped.
The others I can't live without: Ichigo, Renji, Gin, Rangiku, Toshiro, Tatsuki, that one lazy captain (I forgot his name

), Hinamori, and Byakuya. Oh, and Soi Fon, Yoruichi, and Urahara.
I hope we get IchiHime <3. It's much more realistic than IchigoxRukia, which we'll most likely get because anime has to be so cheesy with its couples. IAnd I don't really mind RenjixOrihime. That's kind of hot, if you think about it.
Oh, and definitely GinxMatsumoto. That is like, sex.