it doesn't matter. What matters is your individual taste. If an old, extremely rare tea doesn't suit your palate, then it isn't a good tea for you. Most Dark Teas come in compressed shapes such as Bricks, Cakes, Bowls, or Mushrooms. The original function of the shapes was to ease in shipping since they could be stacked much more secure than loose leaves could. Bricks and cakes are more popular for storing because they are not as tightly packed as the others, which helps them to mature better. If you are purchasing your teas simply to drink, then the shape doesn't matter. If you are purchasing your teas online, find a reputable dealer with a solid guarantee. Check their website. If they seem to know a lot about tea and can offer many varieties, then it is likely that they know their business well.
Storing Dark Tea
Storing Dark teas are easier than Yellow