Many people have already suggested making your Sangria the more traditional way by just adding pieces of fruit rather than concentrated fruit juices— depending on why you are attempting to eliminate the sugars (e.g. for health reasons) this might be the best approach. Another option might be to zest some fruits or use a potato peeler to take long strips of ...
IF avoiding sugars. I would avoid Wine altogether as it contains sugar naturally. Otherwise, you would probably be better off just creating real Sangria.
One option, if you absolutely need an "non-sugar" option, would be to mix the wine with a fruity juice that is sugar-free. Also, not all wines are going to mix well, I would try to get a basic table red ...
Sangria doesn't have "fizzy pop" of any description in it.
It has brandy.
That was where it went wrong, long before the sweetener stage.
Sugar of any description is optional, though personally I'd rather stick my head in a fire than put artificial sweeteners in it, I'd just rather it without anything.
Rioja - Tempranillo, Garnacha etc