Today’s hardwood floors are typically finish with a urethane finish verses shellacs, waxes, penetrating oils, etc. due the the durability and low maintenance a urethane finish provides. There are two options in urethane floor finishes – water-based and oil-based.
Both water-based and oil-based urethane finishes offer good protection, with the biggest difference being being in appearance. Water-based finish go on clear and add no amber tint to the wood floor. This results in less depth and richness in appearance, which in some floors such as maple, may be preferred to keep the white appearance of maple flooring. However, most customers prefer the depth and richness that the oil-based finish adds to the wood flooring.
Typically, a good water-based urethane will cost twice as much as a comparable oil-based finish, hence comes with an upgrade charge if water-based finish is desired. Water-based finishes are very low in odor and that is an important factor to some customers. You will find several writings about applying multiple coats of water-based finish in a single day since it has a quicker drying time than oil-based finishes, however we only apply one coat per day regardless of the finish type chosen.
There is much debate over which is harder, but if you choose a quality finish in either water-based or oil-based, the typical customer will not see any significant difference.
Lastly, to clarify a common misconception regarding floor finishes, NOTHING will make your floor scratch-proof, dent-proof, etc. A floor finish does not make the wood harder. Therefore, big dogs running around corners and dropping things on a floor will gouge the floor regardless of the finish used.