The key distinction is scale and construction vintage. Sun City Summerlin and Anthem are larger, more established communities with more amenities in absolute terms — more golf, more recreation centers, more clubs. Trilogy is smaller, newer, and more intimate.
Buyers who've lived in large planned communities before sometimes prefer Trilogy's scale — it's easier to feel connected to the community when there are 1,400 homes rather than 7,000. Buyers who want maximum amenity options and the deepest social calendar tend to prefer the Sun City communities.
Neither is objectively better — it depends on what you value. I always recommend touring both before deciding.