Rubber technology is a wide-ranging topic with many subtle aspects to it; a small change in the constituents in a rubber compound can dramatically affect the properties of the rubber products made from that grade, either to enhance or detract from performance. 

General guidance on the typical strengths and weaknesses of the family of rubber types is readily available but it is really important to fully understand the environment that a product will be working in; using the garden hose o-ring example, most o-rings on general sale are commercial grade NBR, rather than EPDM, which is the material best suited to the application due to its operating environment. 

The level to which a rubber product is required to perform will then dictate whether a commercial grade of rubber compound will be suitable, or whether a higher grade of material, to a known and provable specification, is needed. That way, the rubber quality will be suited to your application and product needs.