I had a little motorcycle trailer with leaf springs and it had shocks on it. This kept it from bouncing, and especially bouncing like a tow dolly when no bikes were on it.
There is no down-side from having shocks.
Trailers typically do not have shocks because there is nobody riding in the the trailer to complain about the ride quality of not having shocks.
The trailer will handle better with shocks because it will ride smoother, same as your car or truck.
Now, for the question of which is best, the real topic, I do not have an answer.
