One difference in Coke and Pepsi that no one here has mentioned is the sweetener. Some years ago when the store I work at first brought in Mexican bottled Coke I decided to try it and realized that it was a flavor I hadn't tasted in many years. American sodas are made with corn syrup now. The Mexican made stuff is cane syrup like American made ones used to be. Despite what some of the advertisers want to claim it really does change the taste.
Too funny/coincidental... I was discussing taste with a colleague over lunch yesterday because Brussels sprouts were on the menu.
There's a genetic factor to taste that comes into play. I recalled a high school biology teach handing out PTC strips to the class and told us to put it on our tongues and report what we tasted. I was one who tasted it. If you've never tasted it...trust me... it is BITTER! I remember how funny it was to see the people who did not taste it get another strip and try again, chew the paper, roll it around on their tongues. It was like they thought they had to taste it pass the day's assignment. It was the teacher's way to introduce the concept of genetics. (
PTC The Genetics of Bitter Taste for a bit more info. A great lesson that stuck with me.)
PTC and similar substances exist in many vegetables like Brussels sprouts, asparagus, and broccoli. Hence, a reason people don't like those veggies as much. It's not a kid rebelling, such does taste awful to us PTC tasters. I can tolerate occasional Brussels sprouts (barely) and asparagus (more often). Broccoli - no prob. (I ate the sprouts as they were deep fried... anything deep fried should taste better... wrong.)
Could be a similar thing that some people are more taste sensitive to Pepsi v. Coke and corn syrup vs cane. I never have tasted a difference in the two, my wife and sister-in-law swear there's a difference and I am just saying there's none. So, my genes don't care... as long as it's sweet, I like it. They absolutely refuse to drink Pepsi products and will just drink water if no other choice. I think it's genetic... and it's my fault that my sons don't eat broccoli and Brussels sprouts.
(And my oldest has a source for Mexican Coke... no, not the drugs. Well, that's his story and he's sticking to it. But he likes it better than US variety.)