In a bowl, whisk 2 tbsp olive oil, lime juice and zest, chili powder, cumin, smoked paprika, garlic powder, onion powder, chipotle, brown sugar, salt, and pepper for the rub.
Rub mixture evenly over chicken breasts. Marinate 30 minutes at room temp or up to 8 hours in fridge.
Preheat grill or skillet to medium-high; brush with remaining olive oil.
Grill chicken 4-5 minutes per side until 165°F internal temp. Rest 5 minutes, slice.
Combine avocados, tomatoes, corn, onion, bell pepper, jalapeño, cilantro, and garlic for salsa. Season with extra lime, salt, pepper to taste.
Top sliced chicken with avocado salsa and serve.