Most major tractor companies make all different kinds of "add on" pieces for specific jobs. Say an add on mower uses the PTO and hitches onto 3 points on the tractor. Look for the add ons you specifically want, then look for the tractor. Understand just how much horsepower is lost from the drive wheels to the PTO once the add on is engaged. Any tractor should specify in it's book. Know how many RPM the engine has to turn before you engage the PTO. Should be on the tractor itself. The older the equipment, the harder it's going to be to get parts. You want older and cheaper, learn how to weld and keep rust at bay. Paint with used motor oil to keep rust off of surfaces. Know what needs greased and keep up on maintaining everything, including add ons. Learn as much as you can before things get expensive. For instance, there's a company that makes a back hoe, mower and a plow that will go onto a three point hitch. All separate pieces. It's green. Red probably does, too. And others.