In a large drink dispenser or gallon pouring pitcher, add plenty of ice, then add both bottles of wine, brandy, simple syrup, and mango or guava nectar. Stir with a large spoon to combine.
Add plenty of slices of fresh peaches to the sangria and push around with a large spoon.
Refrigerate for 1 hour minimum so the flavors can marry.
Add the cans of sprite and more ice if needed. Serve with additional ice and sprigs of fresh mint, if desired. The flavors will be even better if they are allowed to sit for 1 hour prior to serving.
Notes
If you are short on time, you can use chilled bottles of wine.Use faux ice cubes at the bottom of the drink dispenser for preventing the nozzle from getting clogged.