Preheat grill or grill pan to medium high heat.
Rub chicken breasts with olive oil and season with chili powder, paprika, garlic powder, salt, and pepper.
Grill chicken for 6 to 7 minutes per side until cooked through and juices run clear.
Let chicken rest for 5 minutes, then slice thinly.
Mix ranch dressing with chipotle in adobo to create chipotle ranch sauce.
Warm tortillas on the grill for about 20 seconds per side.
Spread chipotle ranch sauce on each tortilla, then layer lettuce, tomatoes, chicken slices, cheese, and onion.
Roll burrito tightly, folding sides in first, then roll from the bottom up.
Slice in half and serve warm.