As stated above stay with an OPE dealer instead of the big box stores. Since you are mowing a large area you may also want to look at Ferris mowers which have an independent suspension system which will give you the best ride in the business. For a lawn tractor I would look at John Deere in the 500 series, Kubota (might be out of the price range) and Simplicity. Cub Cadet is not what it used to be and I would not buy anything made by Cub today. Personally I would go with a ZTR from a dealer that I want to do business with and shows me he/she wants my business. I would run, not walk, away from any used commercial equipment. The only exception I would make would be if it is sold by a dealer to whom you can return if you have problems. Most used commercial equipment is for sale because it is worn out. You also have no way to confirm any maintenance on the machine since most of it is done by the local talent selling it to you.