> The Coca-Cola Company has been working to increase Coke Zero's popularity, and it is now much more popular than it used to be, but I think Diet Coke continues to be more popular than Coke Zero even now.

This might be a per-country thing -- Coke Zero has always been more popular in Australia ever since it came out (it can be hard to find Diet Coke in vending machines and for single-bottle sales here). Of course, Coke (and Pepsi) can taste different in different countries but I would say the Aussie one tastes pretty similar to the American one.