Our choice: Loose
Why: Most tea bags contain small pieces of broken leaves, while loose teas consist of whole leaves (or at least large pieces), which tend to deliver superior flavor, says Sarah Segal of DavidsTea, which has locations throughout Canada and in New York City. And although tea bags may come in a plastic-sealed box, once you open it and leave it in your cupboard for a year, the tea quickly deteriorates. Finally, there's much greater variety with loose tea (you're often limited to black or green tea in bags).
The only drawback: Inconvenience. It can be hard to tote loose tea to work, for instance. Try tea filters: These little pouches from DavidsTea are biodegradable and chlorine-free; just scoop in your tea, pull the drawstring tight and pour hot water over the bag.