counter top vanity tops must play the dual role of being durable and capable of standing up to water, soap, cosmetics while serving as an ample work surface for morning rush hour in the bathroom. This is no place for delicate, porous (read: easy-to-stain) surfaces. At the same time, the vanity top can be a focal point and a connecting point, where wood cabinets below meet tile wall above, for instance.
The surface you choose for that countertop depends largely on your budget and taste.