I never really have Fanta in the US. I dunno why you would when there's so many better things available?
What I think is interesting is that UK Coke and Pepsi taste the same as US versions and their ingredient lists appear the same... But every other product in their ranges like Fanta, Sprite, 7Up, etc. have drastically different tastes and ingredients. All the UK versions use sugar instead of HFCS, for example, but not Coke and Pepsi.
A lot of people rave about "Mexican Coke" for being a real sugar version, but I HATE that Pepsi Throwback with the real sugar. But I think it's interesting the UK plays the "real" sugar game with all the other products, but not cola. I think a lot of it is what you're used to and overrating of products you can't get.
Lemon Fanta is my favourite flavour and the US doesn't even do it...... In fact, the US doesn't really do lemon soda full stop. Sure there is Sprite and similar, but nothing that is like US lemonade, but carbonated, ya know? Grape, Strawberry and Pineapple are all wrong, imo. I usually like grape flavour things, but the Fanta doesn't work.
Mellow Yellow is my go to soda when it's available in the US, especially if there's a Coke Freestyle and I can get Peach flavour, though I usually drink Sweet Tea if I'm going to get something that isn't water, which is rare tbh.