Most of your original tractor ride ons for domestic work, (under 2 hectres) are made by a handful of manufacturers, the Australian Cox and Greenfields make there own, Rover, they use to be good, but they moved over to the Murray manufactured stuff, and basically its crap. Cox and Greenfield are good, spare parts are plentiful and their drive mechanism is easy and inexpensive to maintain.
Then you move into the ZTR domestic mowers, that is a different ball game and it can be expensive in the long run if you get a dud,the oil pressure grear boxes alone cost about $1000 each, plus fitting. Why the mower blokes are pushing them is that they get higher retail margins on them.
A good make 48" or 52" deck ZTR will cost you about between $11000 - $16000, there are cheaper stuff around, the second hand market is good, but check the running hours, but if you are on acreage and the terrain is marginal....its best to go for quality. This means, seperate oil pump and wheel motors on independant oil pressure lines, so if you damage a oil line, the whole machine will not lose oil and you can still limp home. In having the wheel motor and oil pump in one housing, hit a rock and damage the gearbox, you take out both in one hit $$$$$$$.
There are smaller ZTR's on the market at a smaller price...thinner decks and marginal drive systems..
Good luck treaing through the Ride on mower mine field