Kombucha. It’s fermented so does have a tiny bit of alcohol but not enough to have any effect. I like it because it’s dry, low sugar and has some interesting flavours due to fermentation. Also it’s good for gut health. Bit tricky to get hold of when out though unless you are somewhere cosmopolitan.
At home I’ll have a homemade cordial. Currently have several bottles I made in the summer from redcurrants, ginger and lime. Avoid shop bought cordials now due to the sugar tax so they are either really expensive or full of artificial sweetners.