Place 2 pounds boneless skinless chicken breasts in the bottom of the slow cooker in a single layer if possible.

Sprinkle 1 package taco seasoning and 1 package ranch dressing powder evenly over the chicken.

Pour 1 cup chicken broth over the seasoned chicken.

Cover the slow cooker and cook on low for 6 hours or on high for 4 hours, until the chicken is cooked through (165°F internal temperature).

Remove the lid and shred the chicken with two forks directly in the slow cooker; stir the shredded chicken into the cooking juices.

Serve the shredded chicken in tortillas and top with avocado, tomatoes, cilantro, and ranch dressing.