Hook hands down. Lot more expensive up front but well worth it. You dont have to get out of the truck. You can push the box off where ever you want it no matter what angle or grade you are at. With a cable you have to just let gravity do its thing. Cables are scary I snaped two before we switched to a hook. I have also seen someone else slice through the cab of a truck. It sounds like we use ours about the same as you would. We move equipment all the time on our flatbed, also use it as a dump truck, as well as renting out boxes. I think the hook is going to have a much better dump angle for you.
As far as maintenance goes we greas it once a week and change the hydro oil and filters once a year... pretty easy!!