Aww, I don't mind Horatio's way of interacting with victims & their families. Yeah, it gets to the point where you can predict he's going to tell someone "But we have to solve this crime, because I made a promise to a scared 16 year old girl whose mother was just murdered..." Blah Blah Blah. But somehow, I think it works with Horatio, whereas I don't think that method would ring true with Mac, and who he is. Different backgrounds, different personalities, different ways of dealing with crimes, victims and families. Not meaning that Mac is less empathetic than Horatio, because deep down I don't think he is. He just isn't the guy to wear his heart on his sleeve very easily (even with Peyton). I think his less emotional, more clinical detachment and his "Just the facts, m'am" attitude is what helps him deal with what he sees every day, whereas with Horatio, it's his attachment to the victims that help him make it through his day. Different guys, vastly different ways of dealing with their jobs, but I always thought the two had great onscreen chemistry.
Mac is my obvious favorite overall, but of the three Lab Leaders on the CSI shows, I enjoy the way Mac and Horatio do their jobs. As I said, vastly different, but each method just "works" with each character, IMO.