McDonalds Coke is the correct answer, theirs taste better than any other fountain coke for some reason.
Can otherwise. Glass bottle Mexican Coke is good but costs way too much.
This is the answer. We had a thread on this once. I recall the consensus being the only different variable was the supplied water for mixing and apparently McDonald's uses a water superior to most.
Would love to hear if anyone had more info to confirm or deny. This has always been a mystery I wanted to understand. It's important, dammit.