Victorian Lemonade. You can get it at BevMo* and it’s fantastic - not super sweet, not sour, very lightly carbonated.
- BevMo has a bunch of different ‘old-fashioned’ sodas too. I don’t like carbonated drinks, so I haven’t picked any of them up.
No sugar, caffeine or alcohol? Dude, we’re not gods. 
I like lemon juice straight out of the little plastic lemon.
My favorite is the juice of a lime squeezed into a glass, topped off with sparkling water and ice. And sometimes a pinch of salt. Bliss!
Try the Italian drink chinotto. I don’t like super-sweet drinks either and chinotto is my favourite soft drink. It may be expensive and a little hard to find, though. Try it with a squeeze of lemon.
[Judge Smails]
How about a Fresca?
[/Judge Smails]
Fresca
Seconding tonic with lime in it. You may also consider adding a splash of Rose’s Lime Cordial to tonic water, soda water, or indeed just tap water with ice - it’s very refreshing.
iced tea seems the obvious choice, I’m sure there are some with green tea as flavour (there are here in Holland, and I know from experience there is way more choice in ice tea in the US).
Second on Fresca-
Polar Diet Orange works too.
TAB
Nobody seems to drink it anymore but for me an ice cold can equals happiness.