Have you tried aspartame? I've found that Coke Zero tastes much closer to real sugar than Diet Coke.
I figured the difference between Coke Zero and Diet Coke was branding for people who don't want to drink something labeled as diet.
EDIT: I drink both regularly (including today), and I personally do not perceive difference in taste. YMMV.
Coke Zero => Men
Not saying any of this is a good thing... but it's a thing.
Diet Coke (last time I checked) just uses aspartame.
They taste extremely different
Which doesn't help because most places only serve Diet Coke (which I hate) instead of Coke Zero (which at least is available in most supermarkets)