In a large bowl, whisk together buttermilk, half of the salt, pepper, paprika, garlic powder, onion powder, and cayenne. Add chicken pieces, cover, and marinate in the refrigerator for at least 1 hour.
In a separate bowl, mix the flour with the remaining spices.
Heat vegetable oil in a large Dutch oven or deep fryer to 350°F (175°C).
Remove chicken from the buttermilk marinade, letting excess drip off, then dredge thoroughly in the seasoned flour mixture.
Fry the chicken in batches for 12 to 15 minutes, turning occasionally, until golden brown and the internal temperature reaches 165°F (74°C).
Transfer the fried chicken to a wire rack set over a baking sheet to drain and cool slightly before serving.
Notes
For the best results, allow the chicken to rest on a wire rack for 10 minutes after dredging before frying. This helps the coating adhere better to the chicken.