Despite having little sugar – just 8 grams per 12-ounce bottle (rounded out by natural sweeteners stevia, erythritol, and monk fruit extract) – Aspire's lemon-lime flavor is hard to put down. And even though it's lower in calories than much of the competition, with a mere 25 calories per bottle, Aspire rehydrated and refueled us after a burly hour-long hike, thanks to its cocktail of electrolytes, minerals, antioxidants, and B vitamins. It also tastes just as good warm as chilled, making it great to toss in a backpack or cleat bag. [$30 for an 18-pack;]