Just my opinion...it really depends on how much you like to throw money around, how comfortable you are doing your own wrenching, and what sort of dealerships are within an hour or so of you.
John Deere and Kubota are both significantly higher priced that similarly equipped/capable tractors from LS, Kioti, TYM, or Mahindra. They are also more expensive than Massey, McCormick, New Holland, CaseIH, or Bobcat. (Note: most NH, CIH and Bobcat in that size are made by LS or Kioti. Rural King are also much less expensive than JD or Kubota (made by TYM, but supported by RK). Yanmar makes a great machine, but will approach JD and Kubota in price.
Every manufacturer makes good equipment. Specs will vary, but the significance depends on how you use your tractor. Every manufacturer also will have units that fail.
With a 6' rotary cutter, you are looking at likely a "2nd level" frame size with 25 to 30+ HP coming off of the PTO.
Think about what other tasks you will do with it? How many acres of land will you cut? How dense is the vegetation you are cutting?