IMO, Coke Zero is much better than Diet Coke or the old Tab (which was interesting in its own way). Very recently I bought one can of regular Coke - what used to be called Coke Classic. Chilled it in the fridge and poured it over large cubes of ice.
That stuff is good.
If your deep discount store sells Mexican Coke, you're apparently in luck. It's become a cult thing. Aficionados say it's magnitudes better than Coke made in this country.