What do you like the most about your best friend(s)?

I like everything in my best friend, and i'm not afraid to tell her anything. She does criticize me sometimes, so do I, but I think it's important because if she didn't I would think that she's hypocrit and couldn't have an 'honest' relationship. And I love the fact that she's always there for me, it's reconforting. What about you ? :)