self propelled or pull type combine?

I think that self propeled combines are better than pull types. With the self propeled you dont neesd to worry about something going wrong on your tractor. with a pull type there is more chance of something wrecking because you are using a combine and a tractor. we have a self propeled combine and a pull type. it seems like the pull type is breaking down more often than the self propelled. The self propelled is a MF 750, and the pull type is an MF 851. we have 2 parts combines for the self propelled. They are older combines but they get the job done properly. they only cost about 15,00-2,000 dollars.