About a month ago, I wanted to put a tiller behind a farm tractor. By the time I would get a tiller and a modern tractor that would go slow enough, it would cost a pant load. BTW, I didn't want to get a Ford with SOS. Dad had a 6000 with SOS and it spent more time in the shop than in the field. Ford even recalled our tractor and gave us a newer tractor, which wasn't much better. No SOS in my future.
I purchased a used John Deere 17 hp lawn tractor, hydrostatic drive, with a 30 inch counter rotating tiller. After disking over an acre and half of yard with a Jubilee, raking the trash off to one side, I tilled it with the JD. Was impressed with the results and it really didn't take that long. I then disked it with a 3 ft ATV type disk to put groves in dirt so when it rains, the seeds will fill up the groves and look like I had a grain drill. Just put the seed down Monday, waiting for the rains or snow.
Don't know what you want to do with a tiller behind a tractor. Neighbor has a 6 ft tiller behind a big Massey. His tiller is not counter rotating, so it does leave lots of clumps behind.
I've had both types of tillers and won't buy another tiller that's not counter rotating.
Hope this helps you decide on what to get.