In a large mixing bowl, combine the shredded chicken, barbecue sauce, apple cider vinegar, garlic powder, onion powder, smoked paprika, salt, and pepper. Mix well until the chicken is evenly coated.
Transfer the chicken mixture to a slow cooker. Cook on low for 4 hours or on high for 2 hours, until heated through and flavors meld.
If you prefer, you can also heat the mixture in a saucepan over medium heat for about 10-15 minutes, stirring occasionally, until warmed through.
Toast the hamburger buns if desired.
Serve the BBQ shredded chicken on the buns, topped with coleslaw if using.