Before you choose a bathroom sink (often called lavatories by manufacturers), consider how the sink material will influence the way the sink looks, how durable it will be, and how much maintenance it will require.
Porcelain-enameled cast iron is extremely durable and is easy to care for, but it's heavy and needs a sturdy support system.
Vitreous china has a lustrous surface, is easy to clean, and is the most resistant to discoloration and corrosion. Keep in mind it can chip when struck by a heavy object.
Fiberglass-reinforced plastic can be molded into novel shapes. It doesn't hold a shine as well as other surfaces and is not as durable.
Simulated or cultured marble and other solid-surface materials are handsome, but they may chip, and abrasive cleaners may spoil the finish.