It really bothers me that parents can have a favourite child, so I never did that with my children and won't ever do that with my daycare children. (11 years - this is not an attack at you, I understand what you mean) I do have children in daycare that touch my heart more than others and I have to tell myself, oh yeah, hug that one too. Because there is always one child it seems who is really annoying in the group, I hear ya! But I make a conscious effort to treat them all equally.
I've had a child in chare who was super violent and I had to terminate them. Get the parents to help you make that child stop or I agree with the ladies - get out!