Preheat a grill or grill pan to medium-high heat.
In a small bowl, mix olive oil, chili powder, cumin, smoked paprika, salt, and black pepper.
Brush the chicken breasts with the spice mixture on both sides.
Grill the chicken for 6-7 minutes per side or until cooked through and internal temperature reaches 165°F (75°C). Remove from grill and let rest for 5 minutes, then slice into strips.
While the chicken is grilling, place the ears of corn on the grill and cook, turning occasionally, until charred in spots, about 10 minutes. Remove from grill and let cool slightly.
Cut the kernels off the cobs and place in a large mixing bowl.
In a separate bowl, whisk together mayonnaise, sour cream, cotija cheese, lime juice, honey, garlic powder, and cayenne pepper until smooth.
Add the dressing to the corn kernels and stir to combine.
Add chopped romaine lettuce, cilantro, red onion, and jalapeño to the corn mixture and toss gently to combine.
Divide the salad among four plates and top each with sliced grilled chicken.
Serve immediately.