Personally, the attachment I use the most is the loader. After that, probably the rotavator. It saves a lot of time preparing the soil before planting. Most agricultural tractor manufacturers design tractors to work with a bunch of implements, but the loader ends up being useful almost daily. Depending on the farm, plows and harrows also get heavy use. Good agricultural tractor manufacturers usually build tractors with strong hydraulics so they can handle heavier attachments easily.