This seems to be a common sentiment for some books, especially this one- there are so many characters and only so much "time" to dedicate to each (lest it become a tome); while the main cast gets most of the attention (as they should!) I've noticed I'm not the only one here with love for one of the many secondary characters.I just finished it.
I'd say Mark and Callahan were my favorite characters. I also found Straker to be a cooler villain than Barlow. I liked Barlow, but just wished I got more of Straker as well. I think him and Mark had the makings of a good rivalry after ass kicking Mark gave him.
My favorite section of the book begins when Mike Ryerson starts filling in Danny Glick's grave after the funeral and goes right up until Matt revokes Mike's invitation from his house after Mike has returned as a vampire. Mike is definitely up there for me just from being the centerpiece of my favorite chapter(s).