Big Macs are popular because of the unique combination of ingredients and the distinctive taste of their special sauce. The layer of lettuce, cheese, cucumber, and onion, together with the burger, all wrapped in a sesame bun, creates a balanced and recognizable taste experience. In addition, the Big Mac's special sauce, with its unique and distinctive taste, adds a touch of flavor that captivates customers' palates. The consistency and familiarity of the Big Mac's taste also contribute to its popularity among fast food fans.