Mix the sauce base. In a bowl, whisk together the BBQ sauce, chicken broth, brown sugar, apple cider vinegar, Worcestershire, smoked paprika, garlic powder, onion powder, pepper, and salt. If you like heat, add cayenne or hot sauce.
Layer the chicken. Place the chicken in the slow cooker in a single layer if possible. Pour the sauce mixture over the top, turning the pieces to coat well.
Cook low and slow. Cover and cook on Low for 4 to 5 hours or High for 2.5 to 3 hours, until the chicken is tender and easily pulls apart with two forks.
Low gives the best texture.
Shred the chicken. Transfer the chicken to a cutting board or large bowl and shred with two forks. Remove any large fatty bits if using thighs. Return the shredded chicken to the slow cooker.
Reduce and balance the sauce. Stir the chicken into the sauce.
Taste and adjust: add a splash more vinegar for tang, a pinch of salt for depth, or a spoon of brown sugar for sweetness. If the mixture looks thin, leave the lid off and cook on High for 10 to 15 minutes to thicken.
Serve warm. Pile onto buns with coleslaw and pickles, spoon over baked potatoes, tuck into tacos, or serve with rice and steamed veggies. Offer extra BBQ sauce at the table.