Water, unsweetened tea, unsweetened coffee, milk and countless other non-sweetened or minimally sweetened drinks are way better for you than any sweetened drink though.

"0 calorie" sweetened drinks are bad for you not because of their content but because eating sweet things increases your appetite as a reaction to sweet things being comparatively rare in nature, even if it's not sugar, so it's been proven that you're more likely to overeat and snack between meals (where the snacks are often also unhealthy) following consuming sweet drinks (I can't remember how long the effects stick around for but it's long enough that it'll stretch to your next meal, or make you want a snack before it), regardless of whether that food is sweet or not. Eating more also makes you lethargic so you're less likely to burn the extra calories.

The issue is this can be palmed off by the manufacturer as the fault of the people eating more, when fast food restaurants have anecdotally known this since forever and so include a sweet drink in their meal so that you want a bigger meal that you'll pay more for.

Even if you actively ensure that you're not letting it affect your appetite, for the majority of the general population that is not the case, so in practice they're close enough to being just as bad that it doesn't matter which you have