Other than Coke , Pepsi, Dr Pepper etc. Stuff that is not hard to get . I know about Dr. Browns
Sugar-Free Red Bull is pretty good. A can has about 80 mg of caffeine. If that’s not enough, you can always drink 2 or 3 of them…
I’m fond of A&W Zero Sugar root beer, which is also zero-caffeine.
If you don’t like caffeine, but do like stuff besides the taste of carbonic acid, there is also flavored San Pellegrino.
Lots of choices for no-calorie drinks these days.
not looking for sparkling water
What’s your criteria for a drink being pop vs sparkling water?
Zero sugar Squirt is good. So is zero sugar Canada Dry, especially the cranberry.
It doesn’t have gourmet appeal, but Canada Dry diet ginger ale is my go-to soda. A little San Pellegrino (non-diet) pomegranate and orange soda mixed in is tasty.
I’ll often cut the diet taste with a sugared soda, or, to be healthier, a sparkling water.
Diet Ginger Ale, LaCroix Lemon, a little lime juice… and just a dash of Jamaican rum. This was my working-around-the-yard drink this summer: “Gotta make it tasty, so I’ll drink it all, and stay hydrated.”
NON-recommendation: the new Diet Coke “Dream” flavor. Closest I can liken it to is plum cotton candy… 
For cola I like Diet Rite which is ironic because back in the ‘70’s when diet soda contained saccharine it was the worst tasting tripe on Earth with a horrible aftertaste.
Agreed. It’s not easy to find in my local stores, but when they have it, I buy it.
if it says water or sparkling on the label not interested
The Zero sugar Mountain Dews are good. So are the various Dr. Pepper flavors.
There is Sparkling Ice, which is I guess technically sparkling water but doesn’t taste like it.
The zero sugar A &W root beer is awfully tasty.
I think the Boylan diet cream and black cherry sodas are decent (their diet cola not so much). The black cherry is not outstanding, but just a little dash of tart cherry juice enlivens it up a fair bit (works with all diet cherry sodas and diet colas IMHO). Diet Cheerwine is on the the other end of the cherry spectrum from the Boylan (brighter cherry flavor), but also decent in the same vein.
As with kitap I’m good with many (but not all) of the various zero sugar Mt. Dews, particularly the Code Red cherry-flavored one. You may sense a theme here with all the cherry sodas. But you have to like that very sweet Mt. Dew flavor profile, which isn’t for everyone.
Stewarts diet root beer and orange cream are also both pretty decent. The latter might be best in show in comparison to the original. But as with all diet sodas you have to pay very close attention to ‘best by’ dates. Artificial sweeteners, sucralose perhaps somewhat excepted, IME tend to degrade pretty rapidly towards the end. An expired or even near-expired diet soda tends to taste like vaguely-flavored carbonated dirt.
I find Sparkling Ice more like a seltzer or sparkling juice, in that unlike sparkling waters, I can drink it. Cascade ice is a similar drink of a different brand.
I thought maybe kombucha may fit the bill, but it seems that the sugar content can vary from 5g or so to 20ish, so not a good fit.
Gatorade and Powerade have several zero sugar flavours, if the carbonation is optional.
When I was in graduate school some two decades ago, I decided I was sick of diet Coke, which was my go-to diet soft drink up until then. So I tried every diet soda on the market. Runners-up included diet Barq’s root beer, and diet Sunkist, but the clear winner was…FRESCA. (And not one of the new offshoot flavors; I’m talking about the original grapefruit citrus flavor.)
I drank it a lot over the last 20+ years until very recently when I started cutting back on all soft drinks, including diet soft drinks. My adult son loves it too. He drank it all through college, and commented once that people were generally rather quizzical about it, but when they tried it they invariably liked it.
I can’t find diet/zero sugar Code Red anywhere in my market. It’s frustrating.
Love Fresca and other grapefruit sodas (do they still make 50/50?). But if they have real grapefruit juice in them I can’t have them because of some meds 'm on.
Why can’t it be broccoli I can’t have? I love grapefruit!
They proudly state “less than 1% juice”.