Metal cups are not suitable for hot coffee, like stainless steel cups. Stainless steel is stable at normal condition, but might be dissolution in acid environment. Juice and coffee are acid liquid.
Disposable cups seems clean and convenient, but it is hard to judge the product pass rate. Some manufactures put lots of fluorescent brighteners, which could be carcinogens, to make the cup whiter.
Do not use plastic cups for hot liquid unless the cups are made of food grade plastic. Because plastic cups often contain plasticizes. When filled with hot water, the harmful or poisonous chemicals of plastic are easy to dissolve in hot water. Besides, there are tiny pores in plastic's micro-structure, bacteria and sickness tend to concealed in pores.
Color cups are fascinating, but you'd better avoid using them in microwave oven. The vivid painting on inner surface and gold edge of a cup might bring great risk when heat it. Because when meeting with hot water or high-acid or high-alkaline liquid, the toxic metals in painting, like lead and cadmium could be dissolved in liquid and may cause harm to human body.
Glasses, ceramic and porcelain with colorless and non-glazed inner side, are preferred for hot water, tea and coffee. They can bear high temperature and relatively secure in material.
If pay attention to life personal status, the daily life at home collect, the magnesium quality porcelain and bone substance porcelain be the best of choice. Compare to a general ceramic and porcelain, only hold of burn a connect of make the process and bone carbon to make the bone porcelain seem to be more pure, delicate, deeply agile. Bone china can also slow the speed of coffee temperature drops. But the price tend to be more expensive than general ceramics and porcelains.