I asked about New Coke and the guide gave me a sour look. I guess the question gets asked really frequently.
As far as colas go, Diet Pepsi has a decent flavor profile; it's sweet but not cloying or syrupy. And it has enough of whatever acids or other flavorings to mask / distract from the aftertaste of artificial sweeteners.
That's the one thing that hurts Diet Coke, I think, particularly if it isn't cold.
Reminded me of Pepsi a lot, like a Pepsi made by Coke. Much lighter and sweeter tasting. Honestly probably would have done well if they hadn't used Coke branding on it.
Personally I like cane sugar Coke, or stevia Coke over it. Fun fact Coke is the one beverage I know of that you can buy with five different sweeteners: - Cane sugar - High Fructose Corn Syrup - aspartame - aspartame and acesulfame potassium (Coke Zero) - stevia
I find Coca Cola "Classic" undrinkable. Too tart, for my taste.