Cushion is the thickness of material under the midsole and the firmness of the foam. Most shoes will have different levels of cushion based on their intended purpose. Shoes with a large amount of cushion are usually designated for high mileage runs, versus shoes with low cushion which are better suited for shorter runs.
Comfort is the ability for a shoe to mold to and properly fit your feet while running. Everyone has different feet so everyone has a different opinion on what makes a comfortable shoe, but in general, when worn, comfortable shoes should work with your body and not against it.
Support is the ability for a shoe to correct overpronation and underpronation during the gait cycle. Shoes which are praised for their support often aid in injury prevention, especially among runners who pronate excessively.
A shoe can be deemed both lightweight or heavyweight by wearers. Generally shoes are praised based on weight for either being lightweight and retaining the positive qualities of heavier shoes (like good support), or being particularly lightweight making them good shoes for racing and fast-paced training.
Responsive shoes are designed to give the feeling of gaining energy back with each step, as opposed to feeling dead under your foot. Responsiveness comes from the midsole foam or system in a shoe.
Looks refers to how appealing the design and cosmetic parts of a shoe are. Shoes that are praised for their looks are often deemed stylish and trendy by wearers.
A shoe’s durability is its ability to avoid wear and tear over extended periods of time or mileage. Shoes can be broken into three parts, the upper, midsole, and outsole. All three parts need to be made with good quality materials in order for a shoe to be durable, and often shoes that are made with exclusively hard rubber for their outsole, outlive shoes that use a mix of soft and hard rubber on the outsole.
Running shoes that emphasize performance are generally designed to be lightweight, more responsive, and less cushioned than regular running shoes. With these design choices in mind, performance shoes are best suited for races, speed work, and daily training.
Traction is the ability for a shoe to grip the surface without any slippage. Shoes that are praised for their traction often use some kind of rubber tread or studs on the outsole and are designed for running on gravel, wet grass, mud, and trails.
Shoes that are praised for their breathability help keep your foot cooler and allow sweat to evaporate more quickly, often preventing common problems among runners like blisters and Athlete’s Foot.