How do you like to eat your barbeque? I live in eastern NC, and I almost always get a sandwich rather than a tray. I like the mix of flavors; the coolness/sweetness of the slaw, and the smoky/spicy flavor of the bbq. You don't really get that with a tray. In some cases, the sandwich makes the 'cue- Pete Jones' sandwich is one of my absolute favorites, but I don't care for the tray at all.
If I'm farther west and eating Lexington style, I do tend to get trays more, because the Lexington style slaw doesn't create the same type of flavor mix that you get with a sandwich down east. I like the Lexington slaw, I just think it creates a less exciting sandwich.