01 - Place the chicken breasts in the bottom of a slow cooker in a single layer.
02 - Sprinkle the ranch seasoning mix, garlic powder, onion powder, smoked paprika, and black pepper evenly over the chicken breasts.
03 - Pour the chicken broth and the entire can of diced tomatoes with green chilies, including the juices, over the seasoned chicken.
04 - Cover the slow cooker and cook on low for 4 to 5 hours, or on high for 2 to 3 hours, until the chicken is tender and reaches an internal temperature of 165°F.
05 - Remove the chicken from the slow cooker and shred it using two forks. Return the shredded chicken to the slow cooker, stir to combine with the cooking juices, and let it rest for 10 minutes to absorb the flavors.
06 - Warm the taco shells or tortillas in a dry skillet over medium heat for about 30 seconds per side, or follow the package directions.
07 - Divide the shredded ranch chicken evenly among the warmed taco shells or tortillas. Top with shredded lettuce, cheddar cheese, sour cream, diced tomatoes, and fresh cilantro as desired. Serve immediately.