Done practically every possible job at a hub. In my case it depended on how I felt that particular day.
Unloading: set your own pace, slightly less physically demanding due to having gravity on your side, usually less hours, slightly more dangerous could have boxes from poorly built walls fall on you.
Loading: uneven flow causes wait or go go go periods, sense of accomplishment how many packages you can fit in the trailer or having built a tight final wall in the trailer and putting the load strap or bar tight against it so the is no way the packages will shift fall causing damages, like playing Tetris.