Rinse the rice. Combine rice, water, and a pinch of salt in a pot.
Bring to a boil, cover, and simmer on low until tender, 15 minutes. Rest 5 minutes.
Stir together chili powder, cumin, smoked paprika, garlic powder, salt, and pepper.
Pat chicken dry. Rub with olive oil and the spice mix on both sides.
Sear chicken in a hot skillet over medium-high heat until cooked through, 6–7 minutes per side.
Transfer chicken to rest. In the same skillet, melt butter and add corn.
Cook corn, stirring occasionally, until lightly charred and hot, 5–7 minutes. Season with salt.
Whisk mayonnaise, sour cream, lime juice, and lime zest in a bowl until smooth.
Fold half the cotija, half the cilantro, and the jalapeño into the sauce.
Toss the warm corn with a generous spoonful of the sauce. Reserve remaining sauce for drizzling.
Slice the rested chicken into strips. Fluff the rice with a fork.
Assemble bowls with rice, chicken, sauced corn, avocado, and green onion. Drizzle more sauce.
Finish with remaining cotija and cilantro. Add extra lime juice to taste.