Put the chicken in a large bowl. Add cold water, by the quart, to cover the chicken by about 1 inch. Add 1 tablespoon of salt to each quart of water. Cover and refrigerate for at least 2 hours or overnight.
When you're ready to cook, mix the flour, garlic and onion powders, paprika, and cayenne in a large, shallow platter until well blended; season generously with salt and pepper. Stir together the buttermilk and hot sauce in another large, deep platter or wide, shallow bowl; season with salt and pepper.
Drain the chicken in a colander and pat it dry. Dredge the pieces a few at a time in the flour mixture. Dip them into the buttermilk and then roll them in the seasoned flour again to make a good crust. Put the chicken pieces on a piece of parchment or waxed paper, or on a clean platter, while you heat the oil.
Pour about 3 inches of oil into a large deep pot; the oil should not come more than half way up the sides of the pot. Put the pot over medium-high heat and heat the oil to 375 degrees F on a deep-fry thermometer. Working in batches, add the chicken pieces to the hot oil, 3 or 4 at a time and fry, turning the pieces occasionally, until evenly golden brown and cooked through, about 20 minutes. Remove from the oil with a slotted spoon and transfer to a rack to drain; repeat to cook the remaining pieces. Serve hot.