McDonald's Coca-Cola is especially delicious due to a conglomeration of small factors and a few aspects particular to the brand that sets its Coke apart.
McDonald's gets its Coke syrup delivered in stainless steel tanks to preserve freshness, whereas other restaurants receive it in plastic bags stored inside cardboard boxes.
Per McDonald's, its syrup is then coupled with pre-chilled filtered water before leaving the dispenser to help preserve the carbonation for longer, keeping drinks extra bubbly.
Moreover, McDonald's uses a concentrated syrup and water ratio to maintain flavor even as the ice melts. Their straws are also, so you get more Coke in every sip.
McDonald's has a unique relationship with the Coca-Cola brand, as Coke has helped McDonald’s expand over time and will not sell its syrup at a lower price to other businesses.