Preheat a grill or grill pan over medium-high heat.
In a small bowl, combine chili powder, smoked paprika, garlic powder, ground cumin, salt, and black pepper.
Brush 1 tablespoon olive oil over the chicken breasts and rub the spice mixture evenly over both sides of the chicken.
Brush the corn with the remaining 1 tablespoon olive oil.
Grill the chicken breasts for 6-8 minutes per side or until fully cooked and internal temperature reaches 165°F (74°C). Remove from grill and let rest for 5 minutes.
Grill the corn, turning occasionally, until charred and tender, about 10 minutes. Remove from grill and let cool slightly.
In a medium bowl, mix together mayonnaise, sour cream, lime juice, chili powder (for sauce), and half of the crumbled cotija cheese.
Cut the grilled corn kernels off the cobs and add them to the mayonnaise mixture. Stir to combine.
Slice the rested chicken into strips or bite-sized pieces.
To assemble the bowls, divide the cooked white rice evenly among four bowls.
Top each bowl with sliced chicken, the street corn mixture, sliced avocado, remaining cotija cheese, and chopped cilantro.
Serve each bowl with lime wedges on the side for squeezing over before eating.