Sorry but this one I have to answer with a "who cares"! ALcohol and the amazing beverages that come from it all have carbs/calories. When someone tries to create one with less they take away from the fun and flavorful thing that it is supposed to be.
On a side note, the lowest isn't always the most obvious. When I sold beer we found out that Guniness(the canned version with widget in the bottom) is one of the lowest carb/cal beers out there. Much lighter than Miller Lite, and Bud Light. So Flavor is not always sacraficed.
On the flip side this may be an academic question, and then I would have to say that the lower the alchohol and the less flavor the less of the carbs and cals exist. Alcohols are out then and your left with some of the crappy waterbeers like Martens low carb, and Michultra...
Wine has to much flavor and alcohol