Depends on the type of driving that you are planning to do and what vehicle you are going to use them on. All shocks, including OEM shocks are heavy duty. Often times after market heavy duty means a rougher ride from stock. In commercial vehicles, sometimes the springs are so heavy that shocks are not even needed. So, really, it depends on the vehicle and what you plan to do with it and how it is equipped.

FYI, shocks do not improve the handling of a vehicle, shocks do one thing only and that is cancel out the spring oscillations from road imperfections. Cornering, traction and sway is improved with anti-sway bars and tire choice and pressure, not shocks.

The test for wear in a shock absorber is to jounce the vehicle at one corner and see how many times it bounces after you release it. Most vehicles with good shocks stop right away after like one cycle. If it keeps bouncing more than a couple of times, the shocks may be worn out and need replacing.