I have a "Hustler". I believe it has the heaviest framework by far over all other ztr mowers. My wife mows a couple of acres at home with it and I mow 4 acres at the office. 4 years old and no problems. Only issue is you need to keep the top of the mower deck clean or it will shuck the belt. $3-$4 thousand dollar range.
Here is the link to it: http://www.hustlerturf.com/products....id=3&sobi2Id=1