its really hard to say as the entirety of the suspension system (shocks, springs, control arms, ball joints, etc) will be under a lot of stress and any number of them can fail at any given order. From what i've experienced and learned through schooling is at the very top it would be the shocks themselves if nething as they are what is absorbing the blows of the road. next would probably be ball joints or tire rod ends as constant rough roads may damage them quicker (loosen them or cause tears in their boots). again its really hard to say what will go first as there are many variables that come to play. the car is roughly high enough to check some of these components yourself like if one wheel arch is sagging unevenly or you notice torn rubber boots in your tie rod ends or balljoints. or just have a dealership look over it as when you go in for service they usually do a quick inspection. now the quality of the inspection will vary as some may just look at it with a flashlight and go meh, while some actually test and inspect them thoroughly.
if nething when you are on rough roads going slower will definitely help as it will be less harsh on those components and on your back. And avoid/maneuver potholes and roadkill as a means of being self aware of your surroundings.