Personally, after a long brake from drinking coke/pepsi I can't stand either the original or the zero. I seem to crave the taste sometimes, then I buy one(zero) and it's like "what is this? Why sweetness is literally the only thing that I can taste here?" It feels like they are doubling the sugar in comparison to how I remember it. Most likely it's the same drink, I was just used to the massive sweetener/sugar content before.

My wife had never tried Coke Zero before we met and she also prefers it now.

Not sure what they use in these alternatives but Diet Coke/Pepsi taste pretty bad so it must be a starkly different artificial sweetener.

FWIW, in the US at least, Pepsi Max also became Pepsi Zero.

I suspect both are getting away from the 'diet' moniker because of the fact that people not on an active weight loss diet prefer them, ruining the played out joke of 'haha he ordered 2 burgers and a diet coke.'

Coke Zero is the same as Coke but with newer generation Artifical sweeteners. That’s why many who like Coke end up not liking Diet but like Zero much better.