The common walnut wood that is generally considered better for its quality is the Black Walnut. This type of walnut is prized for its rich, dark brown color, distinctive grain patterns, and exceptional durability. The heartwood of Black Walnut is particularly dense and heavy, making it ideal for furniture, cabinets, and other high-end woodworking projects.

The superior quality of Black Walnut is attributed to several factors. Firstly, its color and grain patterns are highly sought after in the woodworking industry. The heartwood is a deep chocolate brown, while the sapwood is a pale yellow, creating a striking contrast that adds visual appeal to finished products. Secondly, Black Walnut is known for its excellent durability and resistance to decay, which makes it a reliable choice for long-lasting furniture and construction materials.

According to the American Hardwood Export Council (AHEC), Black Walnut is one of the hardest and heaviest of all North American woods, with a Janka hardness rating of 1,010. This rating indicates that Black Walnut is highly resistant to wear and tear, making it an excellent choice for high-traffic areas. Additionally, the wood's natural oils contribute to its resistance to moisture, further enhancing its durability.

Furthermore, Black Walnut is highly valued for its workability. It is easy to saw, plane, and sand, and it holds screws and nails well. The wood also finishes beautifully, taking stains and varnishes exceptionally well, which allows for a wide range of design possibilities.

In comparison to other types of walnut, such as the English Walnut or the Butternut, Black Walnut stands out due to its superior color, grain, and durability. While English Walnut is also a popular choice, it tends to have a lighter color and a less distinct grain pattern. Butternut, on the other hand, is softer and less dense, making it less suitable for heavy-duty applications.

In conclusion, the Black Walnut is the common walnut wood that is considered better for its quality. Its rich color, distinctive grain, exceptional durability, and workability make it a top choice for high-end woodworking projects. The data from the AHEC supports this, highlighting its hardness and resistance to decay, which are crucial factors in determining the quality of wood.