Hardwood

Hardwood floors are durable.  Some woods are more durable then others which is why you should give consideration to the species' janka rating.  Along with the hardness rating, you'll want to learn about the materials used for the construction of the ply layers, and the thickness of the veneer layer (in an engineered hardwood).  Manufacturers of pre-finished hardwood floors have quality finishing processes that can offer the customer a 5-50 year finish warranty on their products.
Hardwoods can improve your home's air quality.  They don’t harbor microorganisms, allergens, or pesticides that can be tracked in from outdoors. Hardwood floors also minimize the accumulation of dust, mold and animal dander.
Wood floors are environmentally friendly as well.  Sourced from sustainable managed forests, coupled with the relatively long life cycle in a home and the ability to biodegrade, hardwood floors are an excellent option.
There are some drawbacks to hardwood, however.  They can be scratched (more durable finishes will help), dented (higher janka ratings will help), and they can be damaged by water.  They also must be maintained within a specific temperature and relative humidity range for the life of the floor.  Even still, hardwoods are hard to beat for the look, and added value to the home!