Season the chicken: Pat the chicken dry. Mix the chili powder, smoked paprika, cumin, salt, and pepper, then rub the mixture over both sides.
Layer the slow cooker: Place the chicken inside and add the corn, garlic, jalapeño, and chicken broth around it.
Cook: Cover and cook on low for 3 to 4 hours or high for 2 to 2 1/2 hours, until the chicken reaches 165°F and shreds easily.
Make the sauce: Remove and shred the chicken. Whisk the sour cream, mayonnaise, and lime juice together.
Combine: Stir the creamy mixture into the corn and cooking juices. Return the shredded chicken and cook for 10 to 15 minutes.
Finish: Stir in the cotija cheese and cilantro. Taste and adjust the lime, salt, or chili powder before serving.