Type of wood: Different species of wood have different hardness, grain patterns, and color. Oak, maple, and cherry are popular choices due to their durability and attractive look. Exotic woods like Brazilian cherry or mahogany are often more expensive but offer unique colors and patterns.
Solid vs. Engineered: Solid hardwood is a single piece of wood, whereas engineered hardwood is a veneer of real wood bonded to several layers of less expensive, high-density material. Your choice may depend on factors like your budget, location in the home, and subfloor material.

Finish: Prefinished hardwood flooring has been sanded, stained, and sealed at the factory, whereas unfinished flooring is finished on site. Prefinished flooring is more convenient, but unfinished flooring offers more customization options.

Grade: The grade of the wood describes its appearance, such as the number of knots or other natural features. Higher grade woods are more uniform in appearance but often more expensive.

The quality of hardwood flooring can be assessed by the hardness of the wood (measured on the Janka scale), the thickness of the wood, the quality of the finish (including warranty period), and the reputation of the manufacturer. The quality of the installation also greatly affects the overall result.

Solid hardwood is made from a single piece of wood, making it durable and long-lasting. It can be sanded and refinished multiple times, extending its lifespan. However, it's more susceptible to changes in humidity and temperature.

Engineered hardwood is made of a top layer of solid wood attached to multiple layers of plywood or other wood-based materials. It's more stable and less likely to warp or buckle from moisture or temperature changes, making it a good option for basements or regions with high humidity. However, it can typically be refinished fewer times than solid wood due to the thin top layer.

The cost of hardwood flooring can vary widely based on the type of wood, whether it's solid or engineered, the finish, the grade, and the installation cost. The Hardwood price per square foot could range from $3 to $15 for the materials alone. Installation costs can add an additional $3 to $10 per square foot.

Consider your lifestyle and the specific needs of your home. For high-traffic areas or homes with pets, choose a harder wood like oak or hickory that can better resist scratches and dents. If you live in a humid area or are installing flooring in a moisture-prone area like a basement, consider engineered hardwood. If you have a specific aesthetic in mind, look at different wood species and finishes to find the one that best matches your style. Always make sure to check the manufacturer's guidelines and warranty conditions for your specific situation.