You mentioned hilly and rocky land. For a smooth ride I would look at the Ferris line of mowers. The suspension system works very well. The IS500z is in your price range but does have a Briggs engine which you may not want. The IS1500z would be around $7,000 but would give you the Kawi engine. Also ZTRs are not the best on steep hills. If you have gentle rolling hills you are fine, but if you are mowing steep hills you might want to reconsider a ZTR.
Scag Tiger Cat 48-inch deck, Kawasaki motor
Lawnboy 10227 2T push mower
Stihl BG86 handheld blower
Stihl BR550 backpack blower
Stihl KM110R kombi system with lots of attachments
Stihl HS45 hedge trimmer 24-inch blades
Echo SRM210 trimmer