In a large mixing bowl, combine the softened cream cheese, shredded cheddar cheese, and shredded pepper jack cheese. Mix until well blended.
Add the mayonnaise, diced pimentos, garlic powder, onion powder, and cayenne pepper (if using). Stir until all ingredients are fully incorporated.
Season with salt and pepper to taste. Mix again to ensure even seasoning.
Transfer the mixture to a serving bowl and smooth the top. Cover and refrigerate for at least 1 hour to allow the flavors to meld.
Before serving, garnish with chopped fresh chives. Serve with crackers, celery sticks, or sliced bell peppers.