I prefer to be naked when I can be or commando when I have to be clothed. On occasion I will wear a jock strap to do something different since I like the feeling of my penis against my body and the feeling of my exposed butt. I was introduced to the jock strap in 7th grade P.E. Class and wore one through 12th grade. It was much later in life that I became interested in buying a jock strap for some additional fun when I could not be naked.
Where can you wear a jock strap and not be naked?
We had to wear jocks starting in 7th grade PE class.
We were told that they were required to provide the support needed to prevent injury. That was repeated from 7th grade through 12th grade. However, they never specified what injury might happen if a jock was not worn.
I've gone online looking for the medical reasons for wearing a jock -- same story -- to provide the support required during physical athletic activities. But never anything specific.
The only real use I've ever found for a jock is while riding a unicycle. A jock keeps your cock and balls pulled to the front and up -- so you don't end up sitting on them. That could be very painful. Tight jeans also work well.
Other than that, my opinion on jocks is essentially the same as for any other piece of clothing -- if I don't have to wear it, I'm probably not wearing it.
Nude when possible; commando when clothing is required.
I own about a dozen jocks, different brands and materials. Some are the old school Bike type jock, and I find them all comfortable.
I tend to work outside, so if the temperature is 50 or higher, I find the jock preferable in keeping cool and dry over other types of underwear. Commando is not always possible at work.