I had my first Coke Zero yesterday, and hadn't been clued in ahead of time about what it was supposed to taste like. I was suprised to find out that it tasted exactly like regular Coke to me. It doesn't quite taste exactly like regular Coke once it warms up though.
I drink Sam's Choice diet cola. The taste is about the same as any other diet cola. But the important thing is that it is only fifty cents for a two liter bottle.
I can't see spending more than that for flavored water.