Black tea is ideal thanks to its high tannin content, which gives it its distinctive color, flavor, and mouthfeel. Its flavor is strong enough not to be diluted or altered by ice.
Keep in mind that loose-leaf black tea will produce a stronger flavor than tea bags. Whether you brew it hot or cold, avoid over-steeping, which can result in a bitter flavor.
There are also many types of black tea from orange pekoe used to make classic Southern sweet tea to Assam, Darjeeling, chai, and Earl Grey, each with unique nuances.