I didn't mean "sweet" in that sense; I meant that your prefs are among the, if not the, sweetest sugary sodas out there (The energy drinks aren't really sodas.), so I assume that their sugar-free versions are similarly sweet.
Pepsi has quite a bit of sugar, and both 7 Up and Mt. Dew have more. (
See this.)
Edit: For a few years I drank 24 cans of Pepsi/day, but after having drank 2 liters (c. 5 2/3 cans)/day for the last 30 or so years I'm now down to 3 or 4 cans/day.