I like Ichimaru mostly because he *seems* complex and (I only watch the anime have not read the manga) am hoping that we get to find out at least a little more about him (yes, I have seen the latest eps, don't want to say more than that, though).
I actually really like Rukia, too. Tough and with a lot of resolve, but not insensitive, has her flaws and weak points but has a great deal of strength and is a great friend to others. I think she's one of my favorite anime females ever.