01 - Place chicken breasts in the bottom of a slow cooker.
02 - Sprinkle ranch seasoning mix, garlic powder, onion powder, smoked paprika, and black pepper evenly over the chicken breasts.
03 - Pour chicken broth and diced tomatoes with green chilies (with juices) over the seasoned chicken.
04 - Cover and cook on low for 4 to 5 hours (or on high for 2 to 3 hours), until chicken is tender and fully cooked through.
05 - Remove chicken from the slow cooker and shred using two forks. Return shredded chicken to the slow cooker, stir to combine with the juices, and let rest for 10 minutes.
06 - Warm taco shells or tortillas according to package directions.
07 - Divide the ranch chicken among the warmed taco shells. Top with shredded lettuce, cheddar cheese, sour cream, diced tomatoes, and fresh cilantro as desired. Serve immediately.