Using a large mixing bowl, combine the shredded chicken, Greek yogurt, Mayonnaise, lemon juice or apple cider vinegar (start with 1 teaspoon), buffalo sauce, garlic powder and onion powder. Mix until all combined. Taste and adjust any seasonings as needed.
Add in the diced red onions, green onions or scallions (if desired) and celery and season with salt and pepper. Mix until everything is combined and everything is nicely mixed. *I'm told that adding gorgonzola cheese (or any blue cheese crumbles) would be an excellent addition. Taste one more time and season with more salt and pepper if needed.
Transfer your buffalo chicken salad to a bowl (covered) or airtight container with lid and chill in the refrigerator for at least 30 minutes (if desired) so that the flavors can meld together.
MAKE AHEAD: if you are making this chicken salad for an event, brunch or lunch, you can make in advance and chill in the fridge overnight. The chicken salad tastes even better the next day! Enjoy in a sandwich, with some greens, in a wrap, with crackers or chips, or just on its own!