BBQ as in, a smoker, or grilled chicken?
Use thighs. More tolerant of overcooking, more moisture, more flavor. If you have to use breasts, get skin on/bone in. Don't overcook - use a thermometer to whatever temperature you're comfortable with.
As far as sauce goes, it's probably your best bet to go buy a few that sound good and taste them. Most commercial sauces are going to be mostly sugar anyway, so read the labels if you're looking for something different. If you happen to live in the northeast, or don't need it right now, I really love
Stonewall Kitchens' sauces. All of them that I've tried. Honey BBQ, Maple Chipotle, and Garlic Peanut are all in my fridge right now. Totally worth the price.