Red Bull Sugarfree has the classic Red Bull taste, but also has a very fake sweetness to it, which is likely caused by the zero-calorie sweetener sucralose.
Compared to the sugar-free, Red Bull Zero tastes truer to the original, making it a better substitute if you want the taste of the original without the sugar.
Despite the name, nothing about Red Bull Green Edition is green. With dragon fruit flavoring and a pinkish-purple color, the green label is out of place.
The watermelon taste gets overpowered by the Red Bull flavor, giving the drink a strange, disorienting flavor that is at turns too strong and too weak.