
Cherry juice is the unfermented juice of cherries, sweet to sour depending on the type.
Pomegranate is the closest match for color and sweet-tartness together. Cranberry gives the acid and a thinner body. Cherry syrup or liqueur brings the flavor with sugar attached, so the drink needs rebalancing rather than topping up.
Sour cherry juice
Prunus cerasus, Montmorency and its relatives: sharply acidic and low in sugar, so it works as part of the souring. A recipe built on it turns flat if you pour the sweet kind.
Cherry syrup and grenadine-style cordials
Sweetened concentrates with several times the sugar and a thicker body: they give sweetness and color and almost no acidity.
Fresh juice keeps a day or two refrigerated and dulls faster than it spoils. Bottled keeps to its date and wants the fridge once open, and an opened bottle of unsweetened juice ferments quietly if it sits.