Combine paprika, garlic powder, oregano, cumin, salt, and black pepper in a small bowl. Rub the paprika mixture evenly over the chicken; let stand for 10 minutes.
Arrange the chicken, onion, bell pepper, and jalapeno pepper on a grill rack coated with cooking spray. Cook the vegetables 4 minutes on each side or until tender. Cook the chicken 6 minutes on each side or until done. Remove chicken and vegetables from the grill; Halve the jalapeno and remove the seeds, then coarsely chop the vegetables. Let the chicken stand for 5 minutes; thinly slice the chicken.
Sprinkle about 3 tablespoons cheese over half of each tortilla; divide vegetables and chicken evenly over the cheese. Fold each tortilla in half over the filling; lightly coat the tortillas with cooking spray.
Heat a large nonstick skillet over medium heat. Place 2 quesadillas in pan; cook 2 to 3 minutes on each side or until the cheese melts and the tortillas are lightly browned. Repeat procedure with the remaining 2 quesadillas. Cut each quesadillas into 2 wedges; serve with sour cream.
Garnish with Avocado-Tomato Salad, posted separately if desired.