Preheat a grill or grill pan over medium-high heat.
Brush the ears of corn with 1/2 tablespoon olive oil and sprinkle with 1/4 teaspoon chili powder, 1/8 teaspoon smoked paprika, and a pinch of salt.
Grill the corn for about 10 minutes, turning occasionally, until charred and cooked through. Remove from the grill and let cool slightly.
While the corn is grilling, season the chicken breasts with the remaining 1/4 teaspoon salt, 1/4 teaspoon chili powder, 1/8 teaspoon smoked paprika, and black pepper.
Brush the chicken with the remaining 1/2 tablespoon olive oil and grill for 6-7 minutes per side, or until cooked through and internal temperature reaches 165°F (74°C). Remove from the grill and let rest for 5 minutes.
Cut the grilled corn kernels off the cob and place in a large mixing bowl.
Dice the grilled chicken into bite-sized pieces and add to the bowl with the corn.
Add the chopped romaine lettuce, halved cherry tomatoes, finely chopped red onion, and chopped cilantro to the bowl.
In a small bowl, whisk together the mayonnaise, sour cream, lime juice, minced garlic, and remaining chili powder and smoked paprika (if any left).
Pour the dressing over the salad ingredients and toss gently to combine.
Sprinkle the crumbled cotija cheese over the top of the salad before serving.