Cascade ice
On the surface it seems to be okay, but people have mixed results with sucralose spiking their insulin, some do, some don’t.
The thing I’m suspicious of though is that every category of the nutrition is listed as zero but the third ingredient is pear juice concentrate which would definitely add some natural sugars.
There is a lovely flavored carbonated water here called “Sparkling Ice” that comes in several flavors. I love it.
And I don’t really lose any weight even when attempting it while I’m drinking it. When I shift back to ice water and a lot of it through the day instead, the scale wakes up again. I’ve gone back and forth on this and have concluded that for whatever mysterious reason it just ‘stalls’ me. Clearly it’s invoking insulin through some other pathway than simple blood glucose.
My friend C. is keto off and on and she says she can’t lose much while drinking diet stuff. Who knows why.
So I guess YMMV.
Drinking diet drinks everyday was shown to cause weight gain (with carb eaters) like 20 years ago. No one seems to remember this now. I think the artificial sweeteners all cause an insulin spike without raising BG levels. Insulin of course causes fat storage. I don’t think there’s a way to test if something you put in your mouth spikes insulin without doing it at a lab. If you look it up most artificial sweeteners are known to spike insulin, some for quite a sustained period of time. Problematic especially if you drink several throughout the day. 
The corp that markets some way of testing insulin in the blood easily from home, not just glucose or ketones, is going to be SO rich.
TAKE MY MONEY I BEG YOU