Pretty much agree with Sam. The other flavours of Tango are better, but for sheer oranginess, I just stick with Fanta. Its a damn good hangover cure too, makes you feel infinitely better.
All the other Fantas are pretty wrong. I used to love the red one, but I overdid that a couple of years ago! The green one is just horrible though! And as for Fanta 'Z', does that stand for Zero taste? Because it really doesn't have any! Dr. Pepper 'Z' is the worst though, its just dark brown water.