Add the chicken thighs and breasts to a large (8-quart) slow cooker.
Pour the entire bottle of BBQ sauce over the chicken. Add the apple cider vinegar, smoked paprika, garlic powder, onion powder, kosher salt, black pepper, and chili powder.
Cook on LOW for 3–4 hours, or until the chicken is tender enough to shred. (This is my favorite method.)
Remove the chicken and shred it with two forks or a hand mixer on low speed.
Return the shredded chicken to the slow cooker and stir it into the sauce.
Continue cooking on LOW overnight. The shredded chicken has more surface area to absorb the sauce, creating an even richer, more flavorful result.
Before serving, stir everything together and taste for seasoning. Add more kosher salt if needed, until the flavors really pop.